Quote Originally Posted by marquee View Post

The B-Pipe or catback exhaust has almost nothing to do with an exhaust system except to get the fumes out you can design it anyway you like and can be customised like a mofo and is usually why is cheaper there is no science to it. The only thing that you need to keep in mind is consisty. If you have headers that the pipe drops into a 3" pipe you would not get a anything lower then 3" due to pressure will be backed up and will be pointless in getting headers. If you have a 2" exhaust you can go bigger however if there is no pressure then that is also bad however a bit bigger can reduce pressure and create a more free flowing exhaust which will enable a slight performance gain.
Exactly what I was thinking, it's jut some pipes with mufflers on it, why pay $$$$ foor them whey they does f all performance wise.

You get a nice deep growl from header/CAT and CAI already and they actually give decent performance gains. Besides, some CAI's are so noisy at WOT you can't hear the fart cannons from inside the car anyway (injen or icebox with k&n filter for example).