a TRUE racer that knows wtf they are talking about would realize that you will lose MAYBE a 1ft-lb at low end with corectly sized (2") dual exhaust, but that you would probably stay the same everywhere else. The reason no one uses them in the REAL racing world is that 2 muffler/that much pipe = tons of unneeded weight. IE: why do it with two what you can do with one if it weighs less?
I say, if you want them, just don't get dual canisters