"My forks only have rebound adjustment - can I modify them (new cartridge?) to have comp. and rebound? What's the best way to improve on these standard forks for ride days?"

We also modify the forks, usually at the same time (your choice), because they also suffer from too much hi-speed rebound and a harsh, square-edged bump feel. At 90kg you are past the range of the rear spring and especially the front spring. To get the best from the bike, you should replace both. The bike will then have a solid planted feel with plushness, excellent braking control and stable cornering.

Front:

• K-Tech Sports/Ride day Conversion
  20SSK Compression and rebound valves, service and set-up and spring. This conversion will give you the best range for road and track use.
• K-Tech Race Bike Conversion
  20SSRK Racebike service, set-up and spring. To take advantage of modern compounded sports tyres or slicks, this kit has the latest technology in valve design and shimstack configuration to give outstanding brake and turn-in control without harshness and provides excellent adjustability for any track/weather situation. Can be modified for Roadwork.

Rear:

• Shock Revalve Service and set-up  and spring (if needed)