set the initial with the "vacuum gauge method" then with that # in hand shorten the slots with the FBO $22 plate to get 36 (initial+mechanical) then toss the heavy spring with the elongated loop & sub in a mr gasket/MP/Transdapt light spring in its place for a start (keep the OE light spring) & mix/match from there staying just under the pinging point at WOT up thru the gears on your hottest/driest (most likely to ping) day then plug in the can to ported & adj it with a 3/32 allen wrench staying (same deal) just under the pinging point in everyday driving under varying RPM/load conditions. CCW slows its curve (amt at a given in hg) but not the total. Bottom line NO pining allowed & there is silent ping & peoples' hearing varies so give yourself a cushion. You want to get close to the line but never over it.