I can't imagine shifting any faster without missing a gear and the Nittos NT555s are new. Should I shift 1-2 at a lower RPM. On that run I shifted at 7000 RPMs in all gears and finished in 4th gear.
HIS (Mine) 2011 Ford Mustang GT/ Rapid Spec 400A: Performance White/ MODS: Black 18x9 (front)/ 18 x 10 (rear) AM Saleen Replicas with Nitto NT555s, STEEDA Axle-Back, BBK Off-road X-pipe, Barton Industries Short Shifter, 3.73's, BOSS intake manifold, BBK 85mm TB, STEEDA 101mm BOSS CAI, SCT SF3/ BAMA Tuned, JLT Oil Sepator, Eibach Pro-Kit, Adj Panhard Bar, LCAs
HERS (Wife's) 2013 Ford Mustang/ Sterling Grey/ MODS: Flowmaster Axle-Back, K&N Drop-in filter