I think its easy to lose sight of the fact thats whats good for one is no good for another. Any standard engine will benefit from a free flowing exhaust period. It might only be a few horses but there is a difference, When tuning starts the difference gets bigger as you would be wasting money on cams and the like if the exhaust system is going to strangle the engine. Then on a full race max effort lump it all becomes critical
edit. a small dyno shootout.
http://www.hondatuningmagazine.com/t...t/viewall.html
Bob