Stock 2g exhaust manifold upgrade over 1g stock

[Enilator]

I took my exhaust manifold off and found some cracks and this is a car i just bought so i have seen how the 2g manifold is a performance gain over the 1g but my question is and im sure this has been asked many times but i havent seen it anywhere, but how much of a hp gain is a stock 2g exhaust manifold over a stock 1g?

 

[Drifte]

i would also like to know, I'll be doin this someday.

 

[Defiant]

4.6 HP, 3 to the wheels.

It's not much, but it's not just a matter of a given HP boost, either. It's about making things flow better, which will help out in reducing lag and easing stress on the turbo.

 

[sphillips91]

I would go with a ported evo manifold. They can be found on many sites, arent much more than a 2g ported manifold and they flow better too.

http://www.turbotrix.com/parts/exhaust.shtml

Evo ported manifold 290
2g ported manifold 260

Seems a no brainer to me, they both bolt right on to the head. Dunno about the stock downpipe, but if your replacing the manifold you may as well get a better downpipe too right? since you got it off and all.