Any higher mileage guys have their belt slip with the stock pulley ??
 

I think mine is , but then again I dunno . This just started to happening to me tonite . I was showing 13.4 lbs of boost on my Aeroforce up till 6K RPM's , then it dropped to 11.4 thereafter and the pitch of blower whine souded like it was fluttering , not like dramatically , but just subltely fluttering . It was repeatable , always would build boost to 13.2-13.6 by 6K then drop off to 11.0-11.4 after to redline . Since my car has never done this before I kinda thru out the stock bypass valve which I havent touched . Guess I will go down tomorrow and try to get another new stock belt and see if that changes anything . My stock belt has almost 21K miles on it now .

....also FWIW , the stock boost gauge did not show the variation , it just stayed pegged at 12.5 .