Theoretically, these should have _less_ pack than the 8.3 piston. The 6.5 config will feel the same on the bench, but on the track it will have more traction and be more consistent (at least in our testing).

What I think is going on is that the 8.3 have too much pack or don't pack at the right time. The 6.5's seem to settle better.

One important note is that the 6.5 pistons work best when you move the shocks to the outer hole in the arm. This increases the piston speed and alters when the piston packs.

Try 450-500 in front and 350-400 as a starting point. The stock pink F and red R springs seem to work well as a starting point.