The killer question!
I used Hot Bodies Megagrid on the rear and Hot Bodies beams on the front of my SC10 at last years SC Shootout they worked pretty well
J Concepts Goosebumps, Proline Calibers / Bowties / Bowfighter and AKA Cityblocks all work as well.
The majority of the track surface is hardpacked dirt that is dusty, jumps / high wear sections are astroturf, and there is now a short grass section as well...