I would agree with Quik. I can't really see how much better 2mm can make in throttle response. Besides, the bigger tb, I would think would cause it to be slower off the line, because it would loose a little more vacuum, and slow the air down through the intake. Also, I would think the larger tb would give you a little more top end, but that is really not where the 8.1 shines. It is down low.
I think tuning out the TM and changing some advance curves will yield the best results. That is what I am going to do next.