[Mk2] [Turbo] How restrictive a stock exhaust is?

[sky-net]

Hi,

I'm actually studying a 300 bhp engine setup (Or maybe a bit more) and i'd like to know if the stock b-pipe is so restrictive as some users have suggested.
I actually run without cats (2,5" dp + stock jdm b-pipe). I've read that a stock exhaust doesn't have 2,5" pipe size all way long, with the b-pipe being one of the biggest flow restrictors.

May i face a power limiting factor (+/-300 hp at cranck) if i leave the stock b-pipe? I could replace it with a straight 2,5" tube if needed.

Do you know if there's any other flow bottleneck in the stock exhaust system?

Regards

[gnzyza]

Not sure on the diameter but would think 2.5 or 2.75 all the way through would be fine. Larger is just a waste and noisier at those power levels.

[sky-net]

Not sure on the diameter but would think 2.5 or 2.75 all the way through would be fine. Larger is just a waste and noisier at those power levels.

Thanks. I agree with you. In the states eveyone says the b-pipe is very restrictive. It's easy to figure out as the 2nd cat is placed there. But i'm not so sure about how restrictive a jdm b-pipe might be.


Regards

[Al-sw20]

The inlet to the stock muffler is a restriction as well. If you are prepared to open up the stock muffler and replace the factory inlet with a 3" pipe, it really frees it up.

[sky-net]

The inlet to the stock muffler is a restriction as well. If you are prepared to open up the stock muffler and replace the factory inlet with a 3" pipe, it really frees it up.

It seems doable. I've read a post explaining how a guy in the States did it. I'm not sure about the involved costs. Maybe buying an aftermarket exhaust system results cheaper. I'll ask. Thanks!