So far no one here has provided empirical data to prove replacing the stock catback will provide the OP any gains. I am with BBS, the stock catback is quiet, that is why i run it. As for exhaust, bigger isnt always better. It is about velocity. at the end of the exhaust stream when the gases have cooled a LOT since they exited the turbo, running a 2.5" axle back or cat back could possiblymove more air due to less turbulence. Then again i also cannot prove that either. I would say you definitely dont need it right away but may become a restriction if/when you go bigger in the future.

 

No, if you want the best performance you get a cat delete

 

Ya I know....I guess we are just missunderstanding one another here. I'm not talking about the Catalytic Converter I was talking about the Catback as in the part of the exhaust after the cat.

 

Somewhere buried here on EVOm or on our site there is testing of the stock catback. It is VERY restrictive. There was a time we made an axle back and thought the muffler was the only restriction, that is incorrect. The actual catback pipe is a huge restriction as well. The catback should be one of your first mods, not one of the last.

 

^^^ Enuff said David is the expert.

The stock catback has a flapper valve in the muffler = very restrictive. The pipe also has some restriction, including the neck down from the cat.

Probably 10-20 hp stock, then much more depending on mods

Milburn

 

If there is anyone who knows, it would be buschur.

An aftermarket cbe has less bends and is bigger in diameter than stock; hence freer flowing and better breathing turbo.

 

Thanks David. All I needed to hear, now how much for that catback shipped to slovenia?