Usual variance is you say +/- 15rwkw, fits into it though whether they have/have not changed it
The 350rwkw run you are only running just over 22psi (or so??)
The final 416rwkw run is 25-27psi. Boost + fuel have given the result there don't forget.
GT-RS's on 20-22psi aren't doing much anyway. You really do need to get 25-30psi into it and hence the 416 run has seen a nice solid punch when combined with the E85
The gains are quite good as it comes up onto boost in the midrange. Not surprised at all you notice it, RWD surely has to be pointless
Although overall, the end result is nothing that -5/2530's can't do (power vs boost wise), with better response...