I am running rich right now. Now say, if I get the Greddy Evo2 exhaust and Helix test pipes, will it lean out my A/F mixture a little? And how much more HP do you think I will be getting with these two mods on? I am at 350WHP right now.

 

Adding test pipes and the greddy exhaust will add a good amount of hp. I'm pretty sure there was a thread posted where they added this exact thing to a greddy kit and got almost 40hp, thats the number i remember at least. I'm not sure how it will affect your A/F ratio though, should probably get tuned just to be safe.

 

I'm actually going down the same path at this very moment . . . I found some helix test pipes and ordered the Y pipe from Gruppe-S . . . . bolt it up to my RSr and we'll see. With our Greddy kit running pig rich (not so bad in the winter ), I am under the impression that the test pipes, Y pipe, and exhaust will lean it out a touch.

G