I recently lifted my 2001 GV V6 AT 4.5" total. Using 3" T6 aluminum spacers and a set of Old Man Emu medium coil springs for a 30 mm additional lift.

My problem is the rear shocks, I replaced it with a longer travel Pro Comp ES 1000. Ride is harsh and I'm not happy with it. Does anybody have a formula of some sort to compute for this:

Travel allowance (remaining length/allowance of the shaft inside the shock body when installed) for optimum down travel and rebound to prevent "bottoming out"