I'm also running the 275/55/16 on GTA fronts. They are what made me realize my old tranny was slipping/flaring. With the new tranny finally in, they hook great! I have them at 28# for the street and can foot brake launch around 4# of boost with ZERO spin. Have not been to the track yet, hope to go on Sunday. MJRWOOD, what kind of air pressure have you used at the track for those 1.5 60s?