[MVR 155]

I forgot to add also that just because you dont hear it pinging that does not mean that your not running too lean. If the premium fuel with higher octane does not do the trick I would suggest getting a fuel pressure gauge hooked up to see if your getting pressure under throttle load, if pressure is good the next step I would take is getting a wideband A/F on that thing and see what the true air/fuel ratio is, with a forced induction set up I would be scared of anything in the neighborhood of 13:1 or higher. Another thing you may want to do if its not done already is get a plug that one heat range cooler along with tightening up the gap by .010

Im not just giving you this info blind..... I have owned a couple of supercharged cars along with having alot of nitrous experience, under artificial asperation you want to be on the rich side vs. lean for safety.