TKX

KosmicKuda said
Have not installed mine yet but simple math will give you RPM change. 4th gear is 1:1 and OD depends on which TKX you buy.

I think mine is .68 OD so if you run 3000 rpm at 70, then .68 X 3000 = 2040

The TKX has the same ratios available as the TKO did.
Mine is a TKO 600 with a .64 overdrive.....that equates to a 36% rpm drop from 4th gear.