There are a couple of things you can do depending on your weight.
I am about 100kgs all up, that includes all the gear.
The standard forks are passable on the road but if you weigh a bit more than 60-70kgs they are going to slow you down at the track.
My sp forks as standard were not to bad until braking into bends off the straight.
Lots of chatter and bouncing off the bump stops.
So i changed the springs to hyperpro used 15wt oil cant remember the air spring length at the mo but its in my notes and can get it if you want as its quite important ref the chatter.
Next you can strip the fork and remove the valve for rebound and damping at the bottom of the cartridge. Its on a screw thread and the end of the thread is peened over but can be ground off.
On the valve is a shim stack now this bit involves a few different size shims and washers but in the end we used a almost but not quite the same size extra shim. Slightly thinner, on the stack this was on top of the standard shim.
This made things a bit firm and still worked well with the 15wt oil but you could change that if you want.
When you reassemble the valve make sure the screw thread is free of oil and use some thread lock to stop it comming undone.
No chatter and the adjustment is more pronounced ie it now works in a noticable way.
Not hard to do and most workshops that do suspension can get the shims. The motocross tuners are good for this and thats where i got mine.
Have now changed the forks to RVF ones and am redoing those.
Hope this helps.