I can't help with the Mangaflow but can second the hatred of droning exhaust. Had this experience with an auto Skyline and aftermarket 'fat pipe' with a nasty 2K rpm drone.Originally Posted by Qube
I've read on the old internet (so of course it is true ) that there is very little improvement to be made over factory. Are you replacing rotten plumbing?
What kind of pipe are you thinking of going with, single wall or double wall? Stainless?
I wonder as the noise through the wall of the pipe can be annoying in it's own right...