hi-flow cat vs testpipe...

[davidlizard]

In a performance optic, which is the best? Does the turbo need a back pressure? I heard different opinion about that...

[davidlizard]

????????????

[mxrz]

HFC = Maybe a very slight shift in power band, but no gains to speak of.
TP = Anywhere from slight, to considerable gains and/or power shift. Depends on setup.

[AudiA4Turbo22]

^^x2!

[MikTip]

HFC=No CEL
TP=CEL

I have the HJS(Milltek) HFC on my K04 equipped with GIAC.

Had a test pipe for 2 years. Loud, and constant resetting of the CEL. Plus I had to R&R the TP every year to pass state inspection!

Bought the HFC, it flows as good as the test pipe, and mets emissions. No CEL, passes inspection, and reduced underhood heat and EGT's. The exhaust is no longer "loud" .

Most people get the test pipe because it costs considrably less than the HFC.

Depending on your ECU chip/flash, no CEL.

Depending where you live, no state inspection.

[kyran A4]

I have been wondering this too. I live in CA and my mechanic told me that the HFC is the way to go considering the whole not having to pay to get it taken out just to pass the smog inspection. he told me that the HFC is also better because the turbo doesn't lose the back pressure so that it keeps the already low amount of low end torque it has as opposed to the TP where it gains hp and sounds louder but loses low end torque. I also posted this question maybe a week ago and i got mixed answers, a lot of AZers love the TP from say euro code and such. I would love to see dyno numbers/ride in a couple of cars who have these setups.

-my 2 cents ^_^

[audikid66]

i had a HFC and ditched it for a test pipe wen i did my k04... i like no cats better.. get sweet gargling sound on downshifts..sometimes shoots lil flames, and sounds a lot throatier.. plus throttle response is great... to be honest pefformance diff between the 2 the TP prob gets you a little bit more power out of it not much tho.. if the CEL will bother you..go with a HFC tho my labree hfc threw a code anyways so it didnt make a diff... TP much cheaper tho.. i'd personally go with a TP

[RLB6]

This is very dependent on your setup. What's your setup?

[davidlizard]

This is very dependent on your setup. What's your setup?

Actually, I'm Unitronic stage 1+, Forge DV, K&N air panel.

I'm going Unitronic stage 2, 380cc injectors, Milltek cat-back, Racetec FMIC,
and 3" ER testpipe or HFC

thank you!

[aaaudiprotein]

Hold on... Isnt apr 1+ or revo stage 2 (for example) suppose to erase the CEL from a testpipe forever?

[RLB6]

Actually, I'm Unitronic stage 1+, Forge DV, K&N air panel.

I'm going Unitronic stage 2, 380cc injectors, Milltek cat-back, Racetec FMIC,
and 3" ER testpipe or HFC

thank you!

I'd say stay with a very low cell HFC, like a 200 cell Labree unit. BTW, Uni s/w has readiness built in for the 02 so you won't get a CEL.

[RLB6]

Hold on... Isnt apr 1+ or revo stage 2 (for example) suppose to erase the CEL from a testpipe forever?

Sure does.

[davidlizard]

I'd say stay with a very low cell HFC, like a 200 cell Labree unit. BTW, Uni s/w has readiness built in for the 02 so you won't get a CEL.

I checked out the Labree website and the HFC for our car is very cheap (250$) compared to Milltek (800-1000$)... It's almost the same price that most testpipe... Is it a good quality?

[aaaudiprotein]

Sure does.

Just from the dashboard or erase it so nobody can see that anymore?

[RLB6]

I checked out the Labree website and the HFC for our car is very cheap (250$) compared to Milltek (800-1000$)... It's almost the same price that most testpipe... Is it a good quality?

It's a solid unit and what I currently run. I went from a ER test pipe, (which I have for sale), to a HFC and I don't regret it.

[davidlizard]

It's a solid unit and what I currently run. I went from a ER test pipe, (which I have for sale), to a HFC and I don't regret it.

Is the testpipe louder than the HFC??

[RLB6]

Just from the dashboard or erase it so nobody can see that anymore?

There's no such thing as just removing a CEL from a visual perspective unless you remove it's bulb/LED . So, yes, the s/w sets it readiness so that it doesn't report as a DTC.

[RLB6]

Is the testpipe louder than the HFC??

Yes but a HFC doesn't cut the volume in half unless you go with a higher celled HFC ( i.e., 400 or a 600 cell unit)

[dougyfresh]

I have a 200cell high flow cat and prefer it. The sound is just right (no raspy noises) and I'm doing fine with power. Plus the car doesn't smell like shit.

[aaaudiprotein]

There's no such thing as just removing a CEL from a visual perspective unless you remove it's bulb/LED . So, yes, the s/w sets it readiness so that it doesn't report as a DTC.

I've heard some people saying that their CEL lights was removed but they still had some problems during emission test or something like that.

[kyran A4]

the hfc doesnt break any emmision regulations does it? I know the TP does.

[widgget]

this is the HFC i am running on my setup:
http://www.techtonicstuning.com/show...rtnum=253.167T

Kyran, we have emission testing in New Hampshire and all the shop did was comment me on the sexy tone of my exhaust when i got inspected.

i get a little bit of surfer smell when i really push it but that doesn't bother me.

[dougyfresh]

/\
that picture is pretty dumb (and annoying) to be adding to every post. please stop that.

[Gondi Stylez]

Does the Labree throw any CEL's? I need a new HFC and in Alberta there is no emmision's testing so that is not a concern.

I'm going to be buying the Milltek exhaust so figured their HFC would be best - but $1000 for it YIKES!

This is for a 3.0Q by the way

[coowhip]

I may be wrong but can't you just put a resistor on the O2 sensor thats on the TP to make it read the proper signal voltage so you don't get a CEL light? find out what the signal is at startup cold and warm and find out what resistor will take it down to that signal voltage...

[pondside36]

I think that idea has been tried with limited results, a simulator module of some kind, perhaps becuase of the varying readings that have to be met at different exhaust flow rates.. just thinking off the top of my head..

[n7plus1]

/\
that picture is pretty dumb (and annoying) to be adding to every post. please stop that.

anyway...theres a reason we cant have pics in our sigs

[audikid66]

labree is a good product but it did throw a cell on my car but didn't on my friends
2003 a4... jus go with a test pipe if you don't mind the smell of gas and being a lil louder.. i like the smell haha :)

[davidlizard]

I just email Labree and they dont have anymore 200 cell HFC. The expectacy of life of 200 cell was to short (6-12 month) So they now sell 400 cell HFC and they claims is just 2-3 hp less than 200 cell HFC.

Is it a good buy? and also, How many cell is the stock cat???

[Nebone]

I have a Fast Insensions 300 cpsi metallic cat in my B5, same part fits the B6 tho. Car does not smell like ass but but did give a considerable power increase, if any. The stock cat flows well, but mine had over 100k on it so I just replaced it plus this one is easier to replace 02 sensors on.

Its a turbo car, so if you want more power, change out the turbo (since that is your hp limiting factor).

I had a diagram of a stock cat somewhere of the stock one and the metal casing has 2 metallic catalysts inside totaling over 1000 cpsi.

[04QuattroTurbo]

The other advantage of not having a CAT would be the ability to use 120 Octane at the track. when I ran a catless MR2 AW11, I love running it on racing fuel, albeit, ten years ago it cost $5 a gallon, on wait that's what we pay for our crappy gas...LOL

By the way, I've talked to a smog mechanic and they think that the state of California will be taking over the operations for testing, repairs, etc. Whereas a private shop will not be running the tests and repairs anymore but some public, bureaucratic State station that you will need to bring your car in for the certificate every two years. The guess is that owning the test equipment will be prohibitive very soon, with many shops investing Thousands on the current setup, which is only a 2-wheel model, in future state requirements, even our AWD cars will have to jump on the dyno and get a sniff of our exhausts while traveling at certain speeds and range.

[Tgr_Clw]

and also, How many cell is the stock cat???

600-800 afaik.

[aaaudiprotein]

So is it worth going with Labree 400 HFC or skip that?

[davidlizard]

I think if you dont have smog test in your area, Go for the testpipe...

[04QuattroTurbo]

I think if you dont have smog test in your area, Go for the testpipe...

Are there states/provinces that don't require a smog cert? In this day of age?

[Gondi Stylez]

Are there states/provinces that don't require a smog cert? In this day of age?

Yep! Alberta!

Canada FTW

[0000VW]

I think if you dont have smog test in your area, Go for the testpipe...

TESTPIPE BABY! know your car, put a testpipe on at a fraction of the cost of a HFC and don't be an idiot and sell it just keep it around for inspection time, the day before throw it on pass inspection. it's easy save the money for something else thats worth it