I kinda agree, the change from one soundset to another is to quick in some places ( e.g. @ 1:14 ) making it sound weird. Needs some work on attack/ decay I guess. In the worst case the samples just do not fit to each other.
Back when I did import Shift Sounds I spend hours because I either hated the transitions when revving up very quickly or when revving up slowly. That was a pain in the ass to exit racer, modify the decay/ attack /min / max values and then test again.