[Mus408]

The availability of the billet metering blocks,make this and other metering block mods easy,but you need a good wide band A/F meter,like an INNOVATE LM-1,to verify results on the track or street.
What you try to do,with the Power Valve Restriction, is use the smallest main
jet size,for best cruise performance,and then adjust the PVR, for best performance at heavier throttle loads,before secondaries start to open.
I've been tuning with the LM-1 for 4 1/2 years,and it can be addictive,chasing the ultimate combo!
Wait till you start tuning the emulsion bleeds/jets! You do that to straighten out the fuel curve.