A common mistaken concept in shim stack tuning is the face shims control low speed damping and the stack taper controls high speed.

Dyno tests and Shim ReStackor calculations show shim stack do not work that way.

The dyno example below from the MXScandinavia thread on Thumper Talk replaces the 0.2 mm shims in the stack taper section with stiffer 0.25 mm thick shims.

The dyno test results show the shim stack is stiffer everywhere across the speed range, not just at high speed. Shim ReStackor calculations (lines) show the same thing.

High speed damping can be stiffened tuning the crossover or softened using a preloading ring-shim (more).

Dyno tests show stiffening the high speed stack stiffens damping force at both low and high speed