I went to 54 pistons in the rear a couple of weeks ago (our track is getting real rough) in order to absorb the bumps better. I found that there was not enough rebound dampening and an the back end started to spring off of every bump. I kept going thicker & thicker on the rear oil and it did not settle the rear down until I got to 55 wt oil and the silver spring, so I went back to the 55 piston & 32.5 oil.