I have to think that it is the KR also. I raced a KR a while back and it was much faster than a gt500. I suspect the KR is very underated because I barly pulled on it in a 530 rwhp GTO that runs low 11s.
It is a bit underrated. I havent gotten mine to the track yet (soon, I hope), but my 09 kr put down 480 rwhp SAE corrected. std was 492