No one that has gotten one of these, hasn't noticed the immediate improvement. There are some before and after dyno's from one or two members here that show the increase. I think SC2150 pointed out that this mod was more about throttle response, but the added HP an TQ on top of that was a plus.
Oh and fwiw I got mine from SC2150 and questioned the same thing as you about the cnc work. Tracy explained it to me same as Ted did you. Needless to say after going for a drive, I knew it was as it should be.
Great mod for the money.