HFC vs Test Pipe vs Downpipe

[tbroesch]

Hey Everyone,

Looking to go Stage 2 on my A4 and I was wondering if there are any benefits for HFC vs Test pipe. I live in an area with no emissions and would have the CEL coded out. So no issues there.
I see the APR sells a "Downpipe Exhaust System" which includes both the down pipe and HFC.

I would like to get just the test pipe as it's cheaper and I have no need to pass emissions.

Thoughts?

[mortimersnerd]

I strongly prefer the HFC for both environmental and smell reasons. The cost difference isn't major, especially used and it makes a major difference in emissions.

[Audibot]

I strongly prefer the HFC for both environmental and smell reasons. The cost difference isn't major, especially used and it makes a major difference in emissions.

Agree with this. The smaller cell count compared to a standard cat means you don't lose much in performance, but it doesn't smell like ass when the car is running.

[mortimersnerd]

Following some douche running without cats sucks. I don't want to breathe their exhaust, and I don't want to do the same to others.

[bluetori]

I've been running a test pipe for years on my Avant and guess what it doesn't stick at all. Not one person has ever said my car stinks.

[Audibot]

I've been running a test pipe for years on my Avant and guess what it doesn't stick at all. Not one person has ever said my car stinks.

You've clearly not driven behind someone without a cat then. I find the smell more offensive than driving behind someone rolling coal.

[mortimersnerd]

I've been running a test pipe for years on my Avant and guess what it doesn't stick at all. Not one person has ever said my car stinks.

I've got more smell on mine just with a HFC and tune.

[bluetori]

You've clearly not driven behind someone without a cat then. I find the smell more offensive than driving behind someone rolling coal.

Okay

[Nano909]

I used a test pipe with my APR stage 2 tune. You get more power out of it vs a HFC. Personally I think those people that can't handle the smell should stop modifying a car. I love the smell during stops in a red light and won't kill the environment.

[mortimersnerd]

Glad you like it. Assuming those around you should shows a meaningful indifference to the needs of others.

[Nano909]

Glad you like it. Assuming those around you should shows a meaningful indifference to the needs of others.

Maybe you shouldn't drive a car, and instead ride a bicycle if so.

[mortimersnerd]

Or just not be a self-centered tool?

[Nano909]

Or just not be a self-centered tool?

You're using a map that requires a higher flowing cat or test pipe. Meaning you're creating more pollution than stock. You have no room to act high and mighty. Like I said, if you really felt that way about the "needs of others" you'dride a bicycle and cut your emissions to 0. But no, here you are driving a car with a turbo and a cat that's more flowing than stock.

[mortimersnerd]

What are you, 12 years old? A HFC pollutes a little more at WOT, but it's not a significant difference at cruise. Even at WOT the car makes about 20% as much pollution. And way less inconsiderate smell.

And my bike is awesome. You should try one.

[Nano909]

What are you, 12 years old? A HFC pollutes a little MORE at WOT, but it's not a significant difference at cruise. Even at WOT the car makes about 20% as much pollution. And way less inconsiderate smell.

And my bike is awesome. You should try one.

So you agree that it's not at stock level? That it creates more pollution? Thanks. I'll stick with the test pipe since it gives me more power.

By the way, don't ever go to a track, it smells a lot like there are cars there without a catalytic converter, I'm sure you'd hate It.

[mortimersnerd]

Rationalize however you want. Running catless is a douche move.

[Nano909]

Rationalize however you want. Running catless is a douche move.

Well that's your opinion and you're entitled to one. Don't call it a "douche move" just because you don't agree with it. You don't need to name call those that chose that route, especially when you yourself aren't using a stock cat. Get over it and move on.

[Audibot]

Personally I think those people that can't handle the smell should stop modifying a car. I love the smell during stops in a red light and won't kill the environment.

That's just your opinion, and you're entitled to one. But I completely disagree with you on that. I'm sorry, but having a constant fart in my face while driving isn't my thing. But hey, everyone has their own kinks.

[Nano909]

That's just your opinion, and you're entitled to one. But I completely disagree with you on that. I'm sorry, but having a constant fart in my face while driving isn't my thing. But hey, everyone has their own kinks.

I don't know what car you've driven but you don't get a "constant fart" WHILE driving. You only smell the fumes and only SOMETIMES while at a red light. Never while you're driving. You may want to actually drive a car with a test pipe before sprouting nonsense.

[mortimersnerd]

Neither of us is referencing smelling your own car. It sucks for the people behind you.

[Nano909]

Neither of us is referencing smelling your own car. It sucks for the people behind you.

Perhaps roll your windows up? Only you can control yourself.

[Necc]

Nano, did you went to a dyno to compare testpipe vs hfc? Or just butt dyno?

[Nano909]

Nano, did you went to a dyno to compare testpipe vs hfc? Or just butt dyno?

I'm sure you can Google the difference and find many dyno graphs to support my comments.

[mortimersnerd]

Perhaps roll your windows up? Only you can control yourself.

It's not all about me. That's the point you seem unable to grasp. Re: power difference, 034's dyno numbers state about 3-5 hp difference, so not much. That's pretty consistent with what I read from the few dyno charts available.

[Nano909]

It's not all about me. That's the point you seem unable to grasp. Re: power difference, 034's dyno numbers state about 3-5 hp difference, so not much. That's pretty consistent with what I read from the few dyno charts available.

That means I'm making 3-5 more horsepower than you. You opted for the lesser route because your nose is sensitive. Preach all you want, but that's making you a hypocrite because you're not using a stock cat.

[bluetori]

I can say that a test pipe makes a big difference my buddy and I have the same cars only his Avant has an 8 speed and mine has better responce than his.

[Necc]

I'm sure you can Google the difference and find many dyno graphs to support my comments.

I know.
I ask you becuase I'm running a testpipe actually but I'll have problems to pass MOT without a cat.
In order to avoid mount/dismount every year a HFC could be a solution, but I don't want to los any power...

[Nano909]

I know.
I ask you becuase I'm running a testpipe actually but I'll have problems to pass MOT without a cat.
In order to avoid mount/dismount every year a HFC could be a solution, but I don't want to los any power...

Here we have people to "help" with that. You can't find anyone in your area to help pass?

[Necc]

I did it but it isn't easy... anyway I'll try again before mounting the HFC.

Is throttle response much worse with HFC?