Well with a 17% installed and a fresh new belt on (535 belt) I have new info on this subject. Using a Genisys Evo 5 scan tool, reading live data I measured a whopping 12.34psi at WOT/Redline in 3rd gear. 32 degrees outside, 800ft elevation. I also noticed, after installing the pulley last night my belt tensioner is showing only about 1/2 of the hole on the tensioner strap (the one you put a pin in to hold in place when doing a belt). I also have the VGS setup on the car, idk if maybe I have a leaky bpv? Suggestions, comments? Leaky BPV? Need to run a 532 belt? I have ruled out wear and tear on the supercharger itself, as I was making a healthy 10.5 psi on stock pulley just a week ago and a stock belt obviously. Do most ppl go back to factory vacuum routing with a pulley or keep the VGS?
I think you might need a shorter belt. the first hole is the one you want to see half of if i'm not mistaken. Maybe double check your belt routing.