cutout and power loss?
You've lost low end torque available, but the peak torque is most probably higher (only now that it probably peaks between 4000-5000 rpm).
Your peak hp and tq #'s most probably increased. It's just the lack of low end makes it feel slower, but your et's will be better.
275/40/17 is a lot of tread also, for a stock ls1. 


