I asked the question about adjusting the powervalve. Here is some great info from the James Dean
The graphs below should help with your tuning.
Keep the following in mind:
--Turning the dolly screw is the ONLY PV spring adjustment that affects below 5600rpm.
--The auxiliary (colored) spring's starting RPM is not changed by turning the screw, so you will only notice the PV colored spring effects above 5600rpm.
--The full open PV RPM is affected by BOTH the dolly screw setting and the spring choice, but the spring is more significant.