I posted some of this info in another thread, but it might be worth a thread and/or sticky of it's own!

Tips for dialing in your Dr Pulley HiT Clutch

Install the HiT clutch as it comes out the package ( ie, no need to change the springs ) to see how it performs

Results:
a) HiT clutch is OK -- means the vehicle is smooth and powerful at take-off and acceleration & hillclimbing is excellent.

b) Vibration at take-off but the acceleration is strong -- means the clutch
engagement (clutch arm springs) is too strong or the vehicle engine RPMs aren't enough to make the secondary HiT clutch mechanism engage from the start. Replace the clutch arm spring with higher tension ones or replace the pillow springs with higher tension springs or replace both. The pillow spring should always be a higher rated spring than the clutch arm spring.

c) No vibration at take-off but acceleration is poor -- means the drive belt might be slipping (ie. the main torque spring is too weak) It’s better to use heavier slider weight and/or "torque spring washer" (these are shims that come with the new clutches for the main torque spring) to clamp the drive belt tighter.

d) if you want to try different pillow spring or clutch spring to check out different performance at different combinations of Pillow/ Clutch springs. Please see the HiT instruction enclosed in the package. And always choose the clutch spring first for the correct engaged rpm and then select the pillow springs. (Pillow spring rating > clutch spring rating)

this is very help full info mike

at this point i am at C. so i will be ordering a red mrp main spring i hope that it makes this thing a beast