I was gonna do this as a poll but there are far too many different brands,so just voice your opinion.I was at Sportbikewest all weekend and came to a few conclusions:
RC51s with Akropovic Carbon cans are too sweet sounding for words.I love that sound.
I dont like a high mount system on the RC51.
Hindle cans sound the nicest on any inline four
D&D cans can make anything sound shitty.Tooooooo loud.
My favourite exhaust sound of all is still a set of Nikons on an RZ500 at 11000 rpm.But I may be slightly biased on that one.