I've heard about performance cam or crank shafts... That's about all I can offer
There's always the obvious but expensive roots of
Full race exhaust system,
Higher flow rate Air filter
Power Commander (injection models only I believe)
Bore out to 700/750 cc
Gas Flowing
These are all just terms I've heard and thought should get thrown in to the mix. I know absolutely feck all about the nitty gritty details.
