arctic gold
gold cat spring you won't loose or drop engagement as much as one would think.......about 4-500 rpm. I use the cat gold spring because it allows my m8 153 to hookup in the powder better on drive away, characteristic of a shorter stiff spring, converesly you don't drop much if any on top rpm.
I run an 07 M8 with 153 pclaw track, DD shim kit y pipe, 68 gram weights +shift assist stock secondary spring with old style helix and adj cap, 44/36 helix. the key in this setup for me is the ability to adjust secondary spring pressure for any snow condition, stock m sleds with the cast no adjust secondary spring pressure HELIX, are a handicap that require setting your sled for a alittle less hook / more rev to cover general conditons when snow gets wet or you jump to high altitude or belts gets a little diry etc etc. When cat went cheap you get........cast ?