The trouble with motorcycle exhausts these days, is that the motorcycle manufacturers make it almost impossible to simply slap a new exhaust system on and get gains.
I can remember seven years ago getting 9 horsepower from just fitting an end can to a Honda 954 'Blade'. We got 15 horsepower from fitting an Akrapovic exhaust system to our Yamaha YZF-R1 the same year too. But now? Well, full exhaust systems are giving more like 5 horsepower, and slip-on cans are at best giving a couple of horses, but more often causing losses. So what's the solution? Fit a can, obviously.
Regardless of the relatively meager power gains at peak rpm, there's always much more to the story. Gains in the midrange are actually where it matters most, and on the majority of modern motorcycle this is where you see the biggest power gains, as you're altering the point at which most motorcycles are strangled to pass though Thai or international emissions tests.
Then there's the aesthetic benefits, and of course there's the acoustic benefit. Kawasaki's original-equipped end can for some smaller models looks a bit like something from a Science fiction movie – though better than its big brother's – and sounds about as aggressive as the sewing machine of our neighbors. So it's gone; replaced with a compact and stylish aftermarket end can.
Like most there days, it's legal with the baffle in, not it it's not, and as per usual we saw a bit of a kick in the nuts performance wise. Yep, it lost both power and torque with the baffle in, all the way through the rev range.
Baffle out though, the aftermarket exhaust system made just something like 1 to 2 horsepower extra power at peak, and hangs onto this extra horsepower all the way to the redline. There's also a little more torque in the midrange.
The noise is a welcome addition too. With the baffle out it's not at all offensive, but loud enough to let the world know you're coming.