Like i stated before, the more you mod the more you'll see a difference. I gaurentee my car wouldn't pull nearly as hard if i had a HFC...

 

even stock level is more than that. And when the Cat. getting hotter, also get more restricted.
more highflow system you put in your car ,TBE ,open intakes ,cams the performance gap will incrase more.

 

3hp max is for NA cars. With turbo cars you will get alot more.

 

everyone complains about the stink of a test pipe. stop running your car in the garage with the door shut. otherwise, i rarely smell mine and when I do, its a sweet smell of unburned fuel

 

Why not give it a try? It only takes about 10 mins to swap the Testpipe or HFC.
It all depends on how the car is set up. some cars respond to the testpipe very well if that is the only bottle neck from achieving the full potential. But some cars have bottle neck somewhere else and you won't see any gain from it.

 

So I ordered this from www.gruppe-s.com

3inch

It came with this:



Now on my current HFC I have a bung for my 02 sensor.

I was told by gruppe-s that I would have to have an exhaust shop weld the check engine light fix into my exhaust and then the 02 sensor screws into the check engine light fix.

I was never told where to have the check engine light fix welded too. The cat-back section or the test pipe itself???

Thanks again for the help.

 

on the Evo 9's the 02 goes into the cat, so you could have it welded right into the test pipe. probably easier then taking out the intermediate pipe.

on my greddy cat back, it had a bung on the intermediate pipe though, so i just stuck the o2 sensor in there.

 

Thanks