Monty wrote:I don't agree with you on the box Cav. An empty box in the system will change how the exhaust gas pulses push and pull (high pressure/low pressure) each other through the system and it can also change the point (normally the exit of the can) at which the shock waves are reflected back towards the engine. This is the reason some short exhausts can reduce power even when the back pressure is lower. In my mind much better to have a straight pipe and an absorptive straight through can.
I'm not on about emptying the box. God only know what that would do to the performance and life of the bike.
The box on the ZX6R is purely a secondary silencer. It's sole function is to reduce noise (which is does so with minimal power loss)
What I'm saying is, take the headers off the bike, drill and pry out the cats (there's usually 2 of them) and then reinstall them and get a tune.
This will result in a bike with a lovely sound, good power, good torque curve, potential for better fuel economy, occasional blue flames and it won't be ear piercing loud. The box gives it a lovely crisp note with only a little rasp which I think is perfect (my opinion, others will differ)