1. Training/Track Days
2. Wheels
3. Tires
4. Suspension
5. Exhaust/fuel mapping
I think that brakes can only be slightly improved because most factory brakes on sport bikes are awesome.
The wheels make for marked performance in acceleration, deceleration and maneuverability.
Tires...they speak for themselves.
Suspension set-up and/or replacement parts are a great way to aid overall performance of the bike.
Exhaust and fuel mapping makes for a smooth throttle response that's critical for fast riding. Not to mention great for lane splitting too. A herky-jerky throttle makes for some interesting rides during lane splitting.
And yes, losing lots of weights really help!!! I'm looking to drop another twenty pounds. I've lost 17-pounds and that really made a big difference. It's like dropping another set of stock exhaust and catalytic converter.
