The brake pads aren't difficult to change. I pulled my front pads last year when a rock got stuck in less than 5 minutes and had them back in.
I heard that EBC makes really good Kevlar brake pads. I got a set for my car and they were a big difference over my stock ceramic pads.
They do make them for the Ninja 500.
Check out
www.newportcycleparts.com or contact Beartooth Kawasaki and see if they carry them.
http://www.newportcycleparts.com Prices are:
EBC Organic (Kevlar) Pads Fronts (FA129-SN): $27.95
EBC Organic (Kevlar) Pads Rear (FA67/3): $24.95
EBC Double H Sintered Pads Fronts (FA129HH-SN): $29.95
EBC Double H Sintered Pads Rear : Not Available
If You Want To Know More About EBC Brakes, check out their website at
http://www.ebcbrakes.com .