A mate of mine yesterday while checking out the bike also asked the same questions about exhausts
He races V8 Sprint cars and did a tour in the states with a premier Nascar team as they needed a bit of a hand????
Says that aftermarket exhausts on bikes are a waste of time and basically cut horsepower.
He's been an Australian Motorcycle champion in his days maybe 6 times before he got into cars.
Says that basically the Major motorcycle manufacturers spend maybe 100's of millions of dollars on exhausts trying to get the maximum horsepower out of the machine while still complying with Californian Pollution laws, maybe the toughest in the world. And nothing gets into America on the road without doing this???
Says that maybe an aftermarket exhaust may work if yah get the chip with it but most likely the chip will only stop the backfiring and hiccups.
Says the way to do it that works is to do the 3 things that work to get the bike to go.
Firstly get the bike to breath
Second get the bike to go bang when it should (Aftermarket) ignition system
Then do the exhausts, something like Vance and Hinze that guarantees performance
With the help of a wiz kid on a dino maybe a 30% increase in horsepower.
Says that everything else is a wank
And he should know he's got more Australian Motorcycle and Car Australian champion ships on the wall than I've had????????