I have had a Tracy Sports TB waiting to go on for a while, it will be matched to Skunk2 Stage 2 (new profile) cams and valve train. Just waiting on the new Skunk2 tensioner to arrive and of I go.
From what I gather Paul at TDI said when he tuned a car with a larger TB it allowed him to give 6% more fuel at the top end. I cannot remember the spec of the car though it had K Pro of course. What that means in actual gains, I am not sure. Though when tuning N/A every bit helps I guess.