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View Full Version : High flow cat or stock cat???



CaSp3r9
12-06-2005, 02:20 PM
I recently blew my stock cat on my 1998 A4 1.8tq[:(], and I'm looking to buy a new one instead of bothering to fix my broken one. But, therein lies the problem. I don't know if I should play it safe and go with the OEM cat ($430 + install), or get a milltek/techtonics high flow cat? I have heard some mixed opinions about HFC's, like they constantly set off CEL's and they can cause problems with your turbo or downpipe... I'm currently running APR software on a stock k03 turbo and I have a Magnaflow cat back exhaust system with a downpipe.
Any input would be greatly apprechiated.
Thanks guys![a4]

juju4uofa
12-06-2005, 02:24 PM
I beleive only the test pipes "cat-delete" will cause a CEL and even that can be avoided. If you've got to get a new cat please don't get OEM definetely go high flow. THe Miltek is better from what I've read but I think it's also about $650. I'd go with the Labree HFC if it were me for $260.

bitterchild
12-06-2005, 02:54 PM
APR has a secondary o2 light kill function. call them.

dbc b5s aren't as sensitive to HFC so you're good down to about 200 cell count

stock cats are only $50 and up used. Don't pay $400+ for a new one.

94jedi
12-06-2005, 03:01 PM
hey I've got a stock cat for you. $50 plus shipping and it's yours. [:D]

offroader1006
12-06-2005, 03:02 PM
ive got a milltek HFC for sale in the classifieds

b00st
12-06-2005, 03:31 PM
Originally posted by juju4uofa
I beleive only the test pipes "cat-delete" will cause a CEL and even that can be avoided. If you've got to get a new cat please don't get OEM definetely go high flow. THe Miltek is better from what I've read but I think it's also about $650. I'd go with the Labree HFC if it were me for $260.

MILLTEK is 799 if you found it for 650 lemme know the link!
i have done quite extensive research into HFCs and cats in general. i posted the info on here so i'm sure you can search and find it. here is a recap though.

Most Milltek cats have a 3 point swirl pattern which is superior to a single point (99% of cats). A single swirl point can do several things such as cone out (destroying the cat, very common) get clogged, or begin breaking down. A tri-swirl pattern avoids all three of these, however is much more difficult and time consuming to achieve. HJS is also the ONLY company that uses the special coating and technique they do to coat their cats (with what I don’t know), but that is another feature that is not included by most. Just because a cat is labeled as metallic doesn’t mean it is… it could have a content of precious metals of such a small percentage if any just for the ability to market it as such. And finally cell count, make sure it is at highest 200…anything more than that is approaching STOCK.

juju4uofa
12-06-2005, 03:45 PM
How does the Labree stack up?

b00st
12-06-2005, 03:50 PM
i don't want to bash so i will offer up information.

they use a ceramic cat w/ metal shell around it. 400 cell count...its really not that high flow. stock cat is a 600 cell unit...so its not really high flow.

like i said you need a metal cat and 200 cell count....not that people haven't been happy with their labree...but there is room for more potential...or just run a testpipe to extract all the potential out of your setup.

the labree and GHL were like the same deals...basically your gonna get what you pay for.

CaSp3r9
12-06-2005, 03:59 PM
Hey guys, thanks for your help!
My dad just ordered me a Techtonics high flow cat for $420. It arrives and gets installed tomorrow! [:D] [drive] I've heard alot of good things about them from Matrix Integrated and fellow A4 1.8t owners who love them and never have any problems with them. I ALMOST went with an OEM cat [eek]!!! I'm really glad I didn't and I can't wait to see how it performs and sounds! If anyone knows, what can I expect as far as HP/TQ gains and sound? I'm currently running APR software and I have a Magnaflow 2.5" catback exhaust system with a downpipe. Is it an overall louder/deeper tone and can you hear the turbo spool up better? Also, does anyone know the cell count on this cat?
Thank you!!

b00st
12-06-2005, 04:03 PM
just give techtonics a call...ask their sales peeps...they will give you the info you need.

b00st
12-06-2005, 04:12 PM
k...just talked to techtonics...
the cat you just bought is a Random Tech Cat....300 cell count, metal spiral wound web. he also mentioned that they've been having problems with CEL lights popping up with that cat...hope it doesn't happen to you.

techtonics will be releasing their own which is a ceramic core 400 cell count at 275.

qtek16
12-06-2005, 04:19 PM
how loud does a test pipe make the car really.....[:D]

CaSp3r9
12-06-2005, 10:57 PM
Originally posted by b00st
k...just talked to techtonics...
the cat you just bought is a Random Tech Cat....300 cell count, metal spiral wound web. he also mentioned that they've been having problems with CEL lights popping up with that cat...hope it doesn't happen to you.

techtonics will be releasing their own which is a ceramic core 400 cell count at 275.

No, I asked and made sure that it wasn't the Random Tech cat.... Jeremy down at Matrix Integrated told me those are very problematic, so I made sure to stay clear of those. When I talked to a Techtonics rep. this afternoon I specifically asked him about the cat I was ordering. I asked him if my car would have any problems passing emissions, he said no. And I asked him if they've ever had any problems with that cat setting off CEL's, he told me "no, noone has ever had any problems with them." Also, on Techtonics' website, when I bought the cat this afternoon, there was a picture and it was marked at $420- which is what I paid. I just looked at it again and now there is no picture and the cat is priced at $295. Do you have any idea why they changed it? Are they now offering a different cat and I took the last of what they had? I don't understand that...[confused]

Did you click on the right cat? It's the one for the A4 1.8t at the very bottom, not any of the universal ones. I sure as hell hope its not the Random Tech cat... I'll be pissed. But if it is, I'm going down there to their warehouse and getting my money back, its only about 30 minutes from my house. =)

94jedi
12-07-2005, 06:33 AM
Originally posted by qtek16
how loud does a test pipe make the car really.....[:D]

on my car w/ stock exhaust it's BARELY noticeable.....I mean barely....If I didn't tell you it was in there you wouldn't know it.

edot
12-07-2005, 09:01 AM
no cat

audidrvr
12-07-2005, 09:42 AM
the butt dyno will notice very minimal gains if any and the sound will be pretty similar to how it already is, maybe slightly better.

b00st
12-07-2005, 10:20 AM
Originally posted by CaSp3r9
No, I asked and made sure that it wasn't the Random Tech cat.... Jeremy down at Matrix Integrated told me those are very problematic, so I made sure to stay clear of those. When I talked to a Techtonics rep. this afternoon I specifically asked him about the cat I was ordering. I asked him if my car would have any problems passing emissions, he said no. And I asked him if they've ever had any problems with that cat setting off CEL's, he told me "no, noone has ever had any problems with them." Also, on Techtonics' website, when I bought the cat this afternoon, there was a picture and it was marked at $420- which is what I paid. I just looked at it again and now there is no picture and the cat is priced at $295. Do you have any idea why they changed it? Are they now offering a different cat and I took the last of what they had? I don't understand that...[confused]

Did you click on the right cat? It's the one for the A4 1.8t at the very bottom, not any of the universal ones. I sure as hell hope its not the Random Tech cat... I'll be pissed. But if it is, I'm going down there to their warehouse and getting my money back, its only about 30 minutes from my house. =)

I called TECHTONICS and asked him...at the cat i am looking it says $420. Is this a high flow cat? can you tell me about it? what is the cell count? He replies yes...its a Random Tech 300 cell count high flow cat. thats how i found about their OWN version there were going to be selling...but he said 275 for a ceramic core 400 cell count cat.....which to me is not good.

I'm telling you the 420 dollar cat is a Random Tech one and has a 300 cell count. There is no Techtonics HFC until now and its a ceramic 400 cell count cat. I told the guy my car and the cat i was looking at on the web and that is the information I got. Call them back and talk to another rep. I bet the $420 cat thats on the web is really a Random Tech one. Never clicked on anything about a UNI cat. Specifically asked about the one for 1999+ Audi A4.

offroader1006
12-07-2005, 01:03 PM
Originally posted by audidrvr
the butt dyno will notice very minimal gains if any and the sound will be pretty similar to how it already is, maybe slightly better.

sounds the same, maybe a little deeper. but the gains on the butt dyno were definitely noticeable.

goldenchild
12-07-2005, 01:10 PM
non the less random tech is high quality with minimum loss in power compared to a test pipe.

SLAM
12-07-2005, 01:22 PM
no cat....

b00st
12-07-2005, 01:41 PM
Originally posted by goldenchild
non the less random tech is high quality with minimum loss in power compared to a test pipe.

yeah it is a 300 cell unit with a metal spiral wound core....all the good things you would look for....and since stock is 600....i would say it should flow decent....obvisously not better than a testpipe could but a 200 cell unit is still the preferred. and even random techtonics said they were having probs with the random tech cats...so i guess you can take'em as the lye.

audidrvr
12-07-2005, 03:06 PM
Originally posted by offroader1006
sounds the same, maybe a little deeper. but the gains on the butt dyno were definitely noticeable.

not on mine...I have the labree
[drive]

juju4uofa
12-07-2005, 04:07 PM
I've heard the test pipe with an aftermarket cat-back is annoyingly loud. If the test pipe makes hardly any difference in sound with the stock cat-back how does that make since?

LaTenTConcepT
12-07-2005, 06:05 PM
the cat delite pipe no longer throws cels any more they now have a sloution for it

CaSp3r9
12-07-2005, 06:19 PM
b00st -

I was mistaken, Techtonics switching around their site confused me. I thought my dad bought the old 300 cell count HFC for $420, but the one they sold us is their new ceramic coated 400 cell HFC for $295 - they even threw in free shipping! [:)] haha
I talked to Colin (?) and he said he has the same cat installed on his A4 1.8t and has never had any problems with it. It's a very high quality cat with good welds and beastly flanges so I know its not going to fail on me which is mainly what I'm looking for. If it adds HP/TQ and sounds cooler, then thats a bonus. I'm a 17 year old highschool student and I don't exactly have alot of money, especially for Audi parts! haha. Never the less, I'm happy with my decision, I just can't wait to get my car back tomorrow!! [drive] They're storing it at the shop over night in their heated garage and are gonna work on it first thing tomorrow morning[:D].
They said it would take about 3 hours to do though because supposedly they have to take out the front passenger side axle, or atleast get it loose enough to slide that huge ass stock cat out of there?? I was just thinking about it though, and wouldn't removing the air box allow for enough room to slide that cat out of there?? I've never taken my air box out before, but isn't that fairly simple? Would it allow for enough room? I don't have my car here, so I can't look at it and see.

peja
12-07-2005, 06:23 PM
Originally posted by LaTenTConcepT
the cat delite pipe no longer throws cels any more they now have a sloution for it


On the B6 Revo's programming circumvents it.

The B5's solutions thus far are akin to snake oil.

peja
12-07-2005, 06:28 PM
Originally posted by CaSp3r9 [/i]

They said it would take about 3 hours to do though because supposedly they have to take out the front passenger side axle, or atleast get it loose enough to slide that huge ass stock cat out of there?? I was just thinking about it though, and wouldn't removing the air box allow for enough room to slide that cat out of there?? I've never taken my air box out before, but isn't that fairly simple? Would it allow for enough room? I don't have my car here, so I can't look at it and see.


When we did mine it came through where the stock air box was. We took a wheel off intitially to get closer to the cat, but no axle tomfoolery.

bitterchild
12-07-2005, 07:20 PM
Originally posted by peja
On the B6 Revo's programming circumvents it.

The B5's solutions thus far are akin to snake oil.

That's b/c revo doesn't deal w/ many b5s and eliminating or modifying the emissions coding is ILLEGAL. you may not care but that company supplying you the file may since it's their ass.

peja
12-07-2005, 07:46 PM
bitter i was refering to spacing the o2 sensors out like on the vw transverse.. and the aw write up on the resistor mod, both work in theory on the a4. but well theory's a great place.. everything works there.

pointing out that the b6 revo software eliminates testpipe caused cels. prob what he heard... unless
"LaTenTConcepT's cat delite sloution" is an engineering marvel about to grace all of us ;)

bitterchild
12-07-2005, 08:49 PM
[confused]

BranCKY3
12-07-2005, 09:00 PM
Originally posted by juju4uofa
I've heard the test pipe with an aftermarket cat-back is annoyingly loud. If the test pipe makes hardly any difference in sound with the stock cat-back how does that make since?

You heard wrong. It really doesn't change the exhaust all that much... maybe a little deeper but that's it. My car is in no way annoyingly loud.

juju4uofa
12-07-2005, 09:30 PM
This is great news! I was going to get a HFC for this reason only. I live in Alabama so emissions aren't a problem; guess I'll be getting the test pipe afterall. Did you install the Borla Catback and the test pipe all at once or seperatly. If seperate, which made the most difference?

BranCKY3
12-07-2005, 09:40 PM
All at once. Spool time got cut down a lot and sounds awesome [:)]

juju4uofa
12-07-2005, 09:52 PM
Awesome! Well sometime close to summer '06 I'll be ready for exhaust; coilovers are first on the list though. I still haven't decided if I'm gonna go with Borla or have custom piping with a Magnaflow muffler. If I go custom will I need a resonator as well? If so, any suggestions?

BranCKY3
12-07-2005, 09:57 PM
Magnaflow would be your best bet if you're gonna go custom.

juju4uofa
12-07-2005, 10:00 PM
A Magnaflow resonator and muffler? Would I need just a universal resonator or specific model?

BranCKY3
12-07-2005, 10:06 PM
You should probably ask a muffler shop before they make it to see what fits. They sell a lot in different sizes and styles.

b00st
12-07-2005, 10:10 PM
Originally posted by CaSp3r9
b00st -

I was mistaken, Techtonics switching around their site confused me. I thought my dad bought the old 300 cell count HFC for $420, but the one they sold us is their new ceramic coated 400 cell HFC for $295 - they even threw in free shipping! [:)] haha
I talked to Colin (?) and he said he has the same cat installed on his A4 1.8t and has never had any problems with it. It's a very high quality cat with good welds and beastly flanges so I know its not going to fail on me which is mainly what I'm looking for. If it adds HP/TQ and sounds cooler, then thats a bonus. I'm a 17 year old highschool student and I don't exactly have alot of money, especially for Audi parts! haha. Never the less, I'm happy with my decision, I just can't wait to get my car back tomorrow!! [drive] They're storing it at the shop over night in their heated garage and are gonna work on it first thing tomorrow morning[:D].
They said it would take about 3 hours to do though because supposedly they have to take out the front passenger side axle, or atleast get it loose enough to slide that huge ass stock cat out of there?? I was just thinking about it though, and wouldn't removing the air box allow for enough room to slide that cat out of there?? I've never taken my air box out before, but isn't that fairly simple? Would it allow for enough room? I don't have my car here, so I can't look at it and see.

thats cool...don't expect too much out of it...400 Cell really isn't too high flow considering the stock is 600....but thats OK you needed it and it will give you better flow than stock. I have a CAI so...yeah I removed my intake and it gives you a lot of room. or your FWD? i never heard of removing the axle to change a cat out. with the intake box out of the way you can get the 3 bolts that bolt to the turbo and then go from the bottom and get those DP bolts and your done.

CaSp3r9
12-07-2005, 10:37 PM
unbolting the cat isnt the problem, they already have the thing unbolted, its just stuck inside my engine bay, it wont come out going up because my stock air intake is in the way and it wont come out going down becuase my axle and heat shield is in the way [:(]
Is taking the stock airbox out fairly simple? isnt it just held in by a couple of bolts? how long would removing it take and would it allow for enough room for the stock cat to be removed?

BranCKY3
12-07-2005, 11:34 PM
Yes the airbox is super easy to take out. Undo the bolt on the passanger side fender that holds it on, unclip the stuff on the top of it and turbo inlet hose + other hoses. Then just take the top off, turn the bottom sideways and pull up.

b00st
12-08-2005, 10:36 AM
yup and then you should be able to pull the cat out from the top.

CaSp3r9
12-08-2005, 04:54 PM
GOT MY CAR BACK!!!
They ended up just taking out the air box, I dunno why we didn't think of that first, but I'm glad we did. So far, so good! No CEL's, my car is a little louder, and a little deeper (I have Magnaflow cat back with a downpipe) --- It sounds AWESOME! [up]
I didn't really notice a big difference in HP/TQ, but there's a little more kick there... and spool up time was cut down, so it accelerates a little quicker [:)] not to mention being able to hear the turbo spool up a little bit better, it sounds really cool.
Well, I'm outta here! I'm gonna go have some fun and show some friends! [drive]

juju4uofa
12-08-2005, 08:38 PM
Sweetness, glad it worked out!!!

S8power
01-11-2006, 05:54 PM
300 cell max, milltek is 200 or such but pretty big compared to others. labrees is about half the size of milltek and 1/2 the price. if it were me y waste your money and pay more for less power, buy a testpipe for 200$, reprogram and call it a day :) for nice turbo sound

b00st
01-11-2006, 10:39 PM
Originally posted by S8power
300 cell max, milltek is 200 or such but pretty big compared to others. labrees is about half the size of milltek and 1/2 the price. if it were me y waste your money and pay more for less power, buy a testpipe for 200$, reprogram and call it a day :) for nice turbo sound

cuz not everyone has a solution for the B5...my car would light up like a xmas tree once i throw a testpipe on...and because of emissions....we need solid solutions...some companies offer that CEL code to be removed...not mine. so now i would be forced to play around with spacers and hope i find the right combination. or try diode tricks on my O2 sensor. both have write ups...both work for some and both don't work for some. sure i want a testpipe or a 200 cell HFC. but i don't want to dick around all day long trying to figure out the proper spacing or soldering diodes on my O2 sensor. for B6 people...there are more solutions...for b5 people we have to be creative and dick around with stupid stuff in hopes that it works. the codes don't always present themselves right away...it could take a while and then it back to the drawing board...is the O2 sensor too close...too far away...clear code....set it different and try again. sounds like a PITA to me. if it was easy i would have done it already.

Hassmeister
01-11-2006, 10:59 PM
Put a Techtonics 2.5" down-pipe and their Hi-Flow Cat in and it's a night and day difference!

Stock Cats are $800... eek!

b00st
01-11-2006, 11:27 PM
i'll defer back to my previous post.

MILLTEK is 799
i have done quite extensive research into HFCs and cats in general. i posted the info on here so i'm sure you can search and find it. here is a recap though.

Most Milltek cats have a 3 point swirl pattern which is superior to a single point (99% of cats). A single swirl point can do several things such as cone out (destroying the cat, very common) get clogged, or begin breaking down. A tri-swirl pattern avoids all three of these, however is much more difficult and time consuming to achieve. HJS is also the ONLY company that uses the special coating and technique they do to coat their cats (with what I don’t know), but that is another feature that is not included by most. Just because a cat is labeled as metallic doesn’t mean it is… it could have a content of precious metals of such a small percentage if any just for the ability to market it as such. And finally cell count, make sure it is at highest 200…anything more than that is approaching STOCK.

stock being 600 cell count
most HFC's on the market are 400 cell count. GHL, Labree, etc...and they actually use a cermanic core instead of metal and use a metal casing around it to protect it. now for a cat...you want the exhaust hot so it can escape faster...so what do you think gets hotter....cermanic cores or metal cores? plus the cell counts are close to stock 400 cell count vs my stock 600. its key...since the cat is hooked up directly to the turbo to have it flow real nice. which will give you a nice early spool up and get your exhaust out of your system. there is a reason cheap ones are cheap and a reason expensive ones are expensive. you get what you pay for. thats why a lot of people like testpipes...its just an open pipe. i think i would even try header wrap on a test pipe to see if that helps it any.

onemoremile
01-12-2006, 09:24 AM
Originally posted by qtek16
how loud does a test pipe make the car really.....[:D]

mine with neuspeed downpipe and exhaust is obnoxious. it can sound very nice but the droning has to go. there's a labree hfc in the garage waiting to go in now.

fwiw, the labree hfc showed up in a magnaflow box.