When does a(1) mandrel bent 3" pipe become a restriction in regards to horsepower? I am asking about the pipe only not mufflers, y's, x's etc. I have searched under many diff titles and am looking for those of you with some hands on experience. Please do not reference a book or tell me to put a cut-out in. THANK YOU, Art this is for the car in my sig

 

two 3 inch pipes with an x or h pipe will support 750-800 hp.

So 3 inch TD's will have lots of growing room.