Okay, I've broken in my R-Spec and I like it! It's lacking a bit on the top end but the power curve is so instantaneous. It definately has more bottom and mid range power than my REX.
Concerning the difference between the regular TR and the R-Spec, there appears to be little. For some reason, it runs much better than a regular TR. I guess the turbo head does make a big difference.
I'm going to use this motor at the next race and see how my lap times compare.
I will be getting another one.