For those of you that know. We measured the size of my after markert head pipes vs my friends stock and the stock has a larger diameter. My end piece has an '1 1/2 hole and he has a '2 modified end cap. My question is could his modded stock pipe out flow my full exhaust system? Maybe even make more power? If so then I may be looking for a set of stock headers and a slip on.

 

What kinda pipe do you have?

I sure can't feel any difference in power with my Yoshi slip-on w/ factory headers, vs. my old RWR full system. Undoubtedly, the RWR headpipe should be capable of flowing more air, due to the smoother curves in the headpipes as apposed to the stocker, but the Yoshi slip-on is about a foot shorter than the RWR system which may help on the other end. The Yoshi is not a megaphone system though (neither is the stock muffler) - I'd guess the RWR would outflow it with serious mods, but the Yoshi apparently must flow as much as a stock motor is capable of breathing anyway, which may explain why I feel no difference in power between the two. Try them both on a 760 and a difference may very well be realized.
Just one comparison for you to chew on, the only one I have!