I am considering installing a header in my EVO...i have stock turbo, HKS DP, HKS cat back B&B cat-delete pipe.

How many HP could i gain with the header?

Will apreciate your help guys

Thanks in advance

 

Consider that headers have the tendency to crack in turbo applications (unless you get some goods ones (321 stainless iirc) and the engine is just a convenient heat pump for the turbo. For stock turbo applications it might be better to P&P the stock manifold and have it coated. It's also good at keeping gases hot.

 

I honestly would not bother with a replacement manifold on the Evo unless your turbo choice (ie something other than stock) necessitates it, or if you want the look factor. The stock manifold is pretty large inside, and not really a whole lot of porting can be done on it

adam