Changing the S-pipe doesnt do much for performance gain from what I have heard...
I am sorry but I dont see how it couldnt help tremendously. When I removed the stock S pipe. It looks more restricting than anything else on the stock exhaust. I keep hearing people say that the S pipe isnt that much of a gain. But never have seen actual prove. Until I see actaul prove I believe the S pipe is one of the most restrictive parts on the stock exhaust.