Dp testing and results THIS IS LONG SUPER LONG

[91gl]

Wondering what a Milltek non-resonated exhaust would sound like with straight pipes (no cats)? Would this be the best option for hp & tq?

Does Milltek make straight pipes? If not, what are my options for this modification?

milltek does not make straight piped and is one of the more conservative companies when it comes to exhaust design. they off a dp design that designed close to stock specs and the exhaust piping is about the same diameter with stock. They just eliminate one set of cats and use high flowing mufflers and your choice of a resonator or none.

My old setup consisted of milltek dp's (gutted, ofcourse) and FI cat-back with spiral core mufflers and an x-pipe. I did this because the milltek dp's are 2.25" while the FI cb is 2.5" in diameter. this allowed me to maintain good low end torque while gaining gobs of power in the top end thanks to the 2.5" CB.



since then i have sold my setup and alot of parts on my car because i was planning on selling it. instead, i am keeping it and more intent to experiment with different setups just like Justin has for the benefit of these forums. Next setup will be a full FI exhaust with once again, gutted cats, but this time i will be going with x-pipe NON RES with the spiral core mufflers in search of more horsepower without the care of losing some low end torque. ill keep you all updated on that.


oh and as for the sound, think Aston Martin

[notachance]

I know this has been asked a bunch of times but concerning the sound, is there a big difference? If I remove the precats and have that with my non resonated milltek exhaust, would it be extremely loud and overbearing? I definitely wouldn't mind being a little louder but I wouldn't want it to sound like a rice rocket.

[91gl]

I know this has been asked a bunch of times but concerning the sound, is there a big difference? If I remove the precats and have that with my non resonated milltek exhaust, would it be extremely loud and overbearing? I definitely wouldn't mind being a little louder but I wouldn't want it to sound like a rice rocket.

It's loud and you will get people breaking their necks to see what flew by but from inside the cabin, you don't hear much. There is so much sound deadening in these cars that with the windows up, you can still hold a conversation without having to raise your voice at all

[notachance]

See I'm worried about it being too loud. Has anyone who removed the pre cats have some kind of comparison to the loudness of it? And what about the resonance? I have the milltek non resonated catback and there is that slight drone if you want to call it that at around 1800 rpms where you kind of have to raise your voice to talk. Is there a much larger range of this with the piggies?

[91gl]

with the windows up you can talk on the phone just fine. its not even that loud at idle. above 5k its very loud. when cruising though, its not bad at all. with a catback like a resonated milltek, with the gutted dp's it should be as loud as a FI full back with the cats

[UnstableOS]

Excellent article..

[duvinclunk]

Word. Nice write up. I may just go around to a few shops to see if I can get my pre-cats removed. I'd go with vast but can't be without my car for longer than a day and don't wanna hassle with the core charge...

[jfunkey]

Def some real great info. Nice to see this exposed. Comming from domestics I can tell you the pre cat thing had me baffled for the longest as this is one of the major things you ditch first in the exhaust system.

The fact that the perfomance companys for the audi seemed to completly drop the ball on this one is kinda upsetting. Then only to have everyone carbon copy the same bad idea.. ha ha well thats biz I guess.


I have said before that Im doing the headers but Im going to see if I can't get vast to do my Dp's here in the next few weeks and do a stock, to piggie to headers run threw

[cbdsm95gst]

This writeup is awesome. But just to be clear, if you take out the stock pre-cat and leave in the main one, you most likely will not pass emissions, right?

I gutted my precat and kept my main cat and was able to pass emissions with my B5 S4 in California. I was running the 02 sensor spacers and my check engine light would pop on and off because of it. I was still able to pass in california and the emissions were still way lower than the state limit.

[wva s4]

Justin, thanks for this and the motor research, its one of the things I missed about the 2.7. ( all the tuning and people trying anything to make power) Can you tell us where Vast relocated the o2 bung to avoid the cell. I am thinking of doing it myself, but only if I can avoid any cell issues. TIA

[SpeedETC]

^ Information on the VAST setup is included in the following thread...

http://www.audizine.com/forum/showthread.php?t=301828

[wva s4]

thanks......

[IronMike]

I am getting my Vast piggie pipes installed on Monday directly from Vast, along with F.I. resonated exhaust. I am also going with the JHM/Vast tune to tie it all together. I will let you guys know what kind of difference I feel in terms of sound and performance from stock. I drive the piss out of my car (not on a track) so I will be able to notice even the slightest increase in torque/horsepower.

[Papachristou]

i couldnt find these on the vast website, im going to shoot them an email. $450 for a few hp would help

justin, what are your thoughts on just vast DPs (precat removed) with stock exhaust for a little while?

[ZachPDX]

justin, what are your thoughts on just vast DPs (precat removed) with stock exhaust for a little while?

I rocked that setup for a few months. When I got my catback I didn't notice any extra performance gains. The piggies will hint at a more aggressive sound that your stock catback will muffle. I had no plans to get a catback until I HAD to hear more of that v8 grunt.

[Papachristou]

I rocked that setup for a few months. When I got my catback I didn't notice any extra performance gains. The piggies will hint at a more aggressive sound that your stock catback will muffle. I had no plans to get a catback until I HAD to hear more of that v8 grunt.

you said you didnt notice any MORE power when you added the catback later.. did you notice a little more top end with the precats removed/piggies and stock exhaust? its on my wifes cabriolet lol, i would LOVE the v8 rumble but she isnt wanting me to mod it any ... i told her she could scare off other drivers with the DPs and and a catback!

[cbdsm95gst]

my setup is quiet untill about 3000rpm. past that its a beast.

[Justincredible]

i couldnt find these on the vast website, im going to shoot them an email. $450 for a few hp would help

justin, what are your thoughts on just vast DPs (precat removed) with stock exhaust for a little while?

Ya try E mailing vast or if your on the west coast try JHM. I think they do it now.

You can do the modified Dp's on stock cat back. It will have a not super great sound but it will work.

The Dp's are more power the Cat back is more sound. ZachPDX touched on the fact. There is going to be power in the cat back depending on what one you get the results are going to vairy.

Ive said it several times and its true. The best chip for your car is a good set of Dp's. The cat back really will help tie it all in and make it sound real nice. But the sound Vs. performance is what you will have to decide

[charliemike]

I gutted my precat and kept my main cat and was able to pass emissions with my B5 S4 in California. I was running the 02 sensor spacers and my check engine light would pop on and off because of it. I was still able to pass in california and the emissions were still way lower than the state limit.

I think those tests are such bullshit. My buddy's 1993 Ford Ranger passed a recent emissions test at half the max for the state of Maryland. Half ... And that truck is a 4-cyl POS.

I'm not surprised your car passed to be honest. I wouldn't be surprised if the machines really were just blinking lights on an empty box to take everyone's $14 a year or whatever.

[Papachristou]

well, im going to add the catback at some point but im kinda low on funds with my engine build and the damn AC going out in this thing! Ill email vast, id rather them do it and put in the spacers or o2 relocate, im in memphis, no WC for me :(

[jfunkey]

well, im going to add the catback at some point but im kinda low on funds with my engine build and the damn AC going out in this thing! Ill email vast, id rather them do it and put in the spacers or o2 relocate, im in memphis, no WC for me :(

Best to just have them do it and consider it taken care of. in some cases its worth the money you save but in this case best to just have it done right and call it a day.

[mightyb28]

Now you have been talking about a dual header system, what about the models that have single header and downpipe. What is the DP setup ( -p----m--)?? I thought it was ( -m------)??? Can we just move the cat south if my second diagram is correct? It is bolt on replaceable. If so i am going to remove the DP and put the cat at the bottom as the DP, or is that to far out of the 12-24" range?

Brain boiling.... Confusion setting in...

[Justincredible]

Now you have been talking about a dual header system, what about the models that have single header and downpipe. What is the DP setup ( -p----m--)?? I thought it was ( -m------)??? Can we just move the cat south if my second diagram is correct? It is bolt on replaceable. If so i am going to remove the DP and put the cat at the bottom as the DP, or is that to far out of the 12-24" range?

Brain boiling.... Confusion setting in...

Lots of variables. Is this is a V8 your talking about?

[sp0da]

yeah been there done that. pay the lousy $450. save yourself hours of frustration. time is money. i've tried to use a crowbar in there and all sorts of things. not on my car...but others who wanted to do the piggies themselves. even on the b5 s4s. PITA!!!!!

I just finished this project this weekend on my car, and PITA doesn't even begin to describe it. Torture! Unless you have access to an incredible arsenal of tools, do not attempt!
$450 sounds like a smoking deal.

Great write-up, thanks OP! I can honestly say it feels like a significant difference with the new piggies.

[Justincredible]

I just finished this project this weekend on my car, and PITA doesn't even begin to describe it. Torture! Unless you have access to an incredible arsenal of tools, do not attempt!
$450 sounds like a smoking deal.

Great write-up, thanks OP! I can honestly say it feels like a significant difference with the new piggies.

It can be an adventure getting the cats out. I have to agree with you, for the 450$ best go get the OEM gutted drop in ones.

Its hard to make sure you get all the cat bits out from your main cat to. Several bits that fall down there while your pounding them out can be a hassle.

I liked the idea on mine where I just put a pipe in place of the cat section. But for most people its not going to help with the visual inspection at the dealer or at the emissions area. Not only that but I don't like the idea of metal shavings falling into the main cat when your cutting off the pipe for your pre cat.

[pavukS4]

Great thread Justin! Thanks! This is something you don´t find any information about here in Europe.

Does anyone of you have any soundclips, I would like to go for the piggies, but would like to hear the sound of them with any catback. I couldn´t find any good clips on youtube:-(

Regarding the Vast piggies - is it possible to get them shipped without sending them my system back? So I would keep my system as well and get the one with piggies shipped from them. Any idea of the cost then? Maybe I´m blind, but I didn´t find that option on their web.

Thanks!

[Justincredible]

Great thread Justin! Thanks! This is something you don´t find any information about here in Europe.

Does anyone of you have any soundclips, I would like to go for the piggies, but would like to hear the sound of them with any catback. I couldn´t find any good clips on youtube:-(

Regarding the Vast piggies - is it possible to get them shipped without sending them my system back? So I would keep my system as well and get the one with piggies shipped from them. Any idea of the cost then? Maybe I´m blind, but I didn´t find that option on their web.

Thanks!

I think you might have to call, or E mail them direct. Also try JHM

[tylerS]

justin when are you going to update the teardown thread :(

[brad65ford]

Finially gutted the stock dp (only pre-cats). Wasn't bad at all to do with a air chisel (about 20 mins to gut) the pain in the ass is the removel of the dp as expected. Sorry if I'm writing like crap I'm tired as hell. I also did snub mount, Magnaflow cat back, and front rotors and pads today. All and all its hard to say how much the performance difference I feel since I did the catback also, but I don't feel that much of big difference even with both cat back and dp's gutted. Will report back when I have some time on her and the Stage 2 flash. Also no cel light ........ yet.