I'd (1) set initial with "vac gauge method" (2) with that number in hand shorten the slots (per the chart) to get 35 total (initial+slots with can capped) (3) mix/match springs so you are just under the pinging point at WOT up thru the gears on your hottest/driest day (4) then plug in/adj the can (CCW with a 3/32" allen wrench makes it come in slower) and you want to be just under the pinging point in everyday driving under varying vac levels/RPM levels on your hottest/driest day. Mr gasket has a light spring kit 925B as does MP (the 925B might b e the mr gasket number. I would toss the heavy spring with the long loop on one end. spring rate is linear no matter which ones you use (ex for the long loop one that I would toss). here's a chart for #3 just for reference (if I can post it) but go by pinging & there is silent pinging so have a slight cushion