Stock downpipe with HFC and Aftermarket exhaust?

[briansubsist]

Is anybody currently running an aftermarket catback exhaust with a HFC but using the stock down pipe? There isn't anything wrong with doing this is there? It seems like most of the down pipes only provide some additional noise but not anymore power. Thanks for any input.

[Grippy]

My understanding is the only performance to be gained from the turbo back (using stock turbo) is in the cat itself. Anything else may be more for looks/sound.


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[blbroo]

I think a lot of people have an HFC, stock downpipe and aftermarket exhaust


#pedalresponce

[van462]

Look at it this way. It you are connecting to the HFC using a stock size flange and the exit is the same size as well, how much can you possible gain.

[briansubsist]

Look at it this way. It you are connecting to the HFC using a stock size flange and the exit is the same size as well, how much can you possible gain.

Ha! Good point. :)

[MagnaFlow]

No problem with that at all! Quite a few owners run a similar setup to that to gain a little power without the smell and CEL issues.

[s4baby]

This is the direction I'm heading because I don't want a loud exhaust.

[Liquid Smoke]

what about an HFC with a stock exhaust as well? i had an OEM S4 quad exhaust fitted to mine, it's mainly just the back half of the S4, nothing up front has changed from the stock A4 exhaust. and i may want to Stage 1/2 later on. i'm not too worried if i dont get too much of a power increase with the HFC with stock exhaust, but will the sound be ok? i know the HFC makes it a bit deeper, but will it sound too raspy or off or anything with the stock exhaust? my original cat is starting to go bad i think, and i'm wondering if i should just use the opportunity to get an HFC or just get a normal oem cat. i know i won't get power now but later on if i go Stage 1/2 i would get something, but just want to make sure the stock exhaust isn't going to make the HFC a bad choice.

[inv3rtig0]

what about an HFC with a stock exhaust as well? i had an OEM S4 quad exhaust fitted to mine, it's mainly just the back half of the S4, nothing up front has changed from the stock A4 exhaust. and i may want to Stage 1/2 later on. i'm not too worried if i dont get too much of a power increase with the HFC with stock exhaust, but will the sound be ok? i know the HFC makes it a bit deeper, but will it sound too raspy or off or anything with the stock exhaust? my original cat is starting to go bad i think, and i'm wondering if i should just use the opportunity to get an HFC or just get a normal oem cat. i know i won't get power now but later on if i go Stage 1/2 i would get something, but just want to make sure the stock exhaust isn't going to make the HFC a bad choice.

HFC with stock exhaust does not sound raspy at all. It increases the tone a bit, gives it more of a low grumble, but its very subtle. Also, you will get a performance gain right out of the gate, even without a tune. Its claimed to be somewhere in the 20hp range. I ran stock tune + HFC for a few months before going stage 2 (skipped stage 1), and I definitely felt the power bump with just the HFC.

[blbroo]

HFC with stock exhaust does not sound raspy at all. It increases the tone a bit, gives it more of a low grumble, but its very subtle. Also, you will get a performance gain right out of the gate, even without a tune. Its claimed to be somewhere in the 20hp range. I ran stock tune + HFC for a few months before going stage 2 (skipped stage 1), and I definitely felt the power bump with just the HFC.

+1

I did the same


#pedalresponce

[RW12]

HFC with stock exhaust does not sound raspy at all. It increases the tone a bit, gives it more of a low grumble, but its very subtle. Also, you will get a performance gain right out of the gate, even without a tune. Its claimed to be somewhere in the 20hp range. I ran stock tune + HFC for a few months before going stage 2 (skipped stage 1), and I definitely felt the power bump with just the HFC.

With that setup (HFC and stock exhaust), did you get the smell that some people talk about? I've got 2 kids that occasionally ride in the car with me and I don't want any stinky gassy smells in the car.

I'm currently stock tune as well, but was about to get Unitronic stage 1 in a few weeks time.

[inv3rtig0]

With that setup (HFC and stock exhaust), did you get the smell that some people talk about? I've got 2 kids that occasionally ride in the car with me and I don't want any stinky gassy smells in the car.

I'm currently stock tune as well, but was about to get Unitronic stage 1 in a few weeks time.

No stinky gassy smells with the HFC. You only have to worry about that if you go catless (ie, test pipe).

[adamazing]

I've ran an HFC, Stock DP, AWE Quads for over a year now. No issues what so ever.

Some companies sell integrated DP's that are the Catalyst + DP, while others sell just the HFC and/or DP separately. It's all mix and match for the most part. A standalone DP is basically just for additional acoustics.

[RW12]

No stinky gassy smells with the HFC. You only have to worry about that if you go catless (ie, test pipe).

OK, that's great to know. I think I may invest in the HFC then before the tune.