OK guys, I had a chance to try my switchable TRE (5th gear, homemade) out on the racetrack yesterday. 2001 Busa. They do work as advertised on the timing retard. I tried it both ways and there is a big difference in the way the power delivers. We had intermitent showers all day so the track was wet, then dry and then wet again. Once, when coming out of turn 11 and the track was ALMOST dry, I got on it hard and the RPM screamed but the bike didn't accelerate. I was smoking the rear. In turn 3A with oil and light rain the back end came around (but recovered) when I barely touched the throttle. Slick as butter! Leaning in, out of turn 7A, a slow twist of the throttle caused the front end to lighten up and it washed out and then recovered. When the track dried, power was not an issue unless really leaned over. 12 bikes went down out of 60 in these conditions.
Later with the TRE off, I had more manageable power deliverly if the RPMs were low. The torque came on "soft" and had much more tolerance for agressive throttle movement when under 5000 RPM. The power surge coming out of timing retard at 5000 RPM was destabilizing however, especially leaned over on a damp sweeper while accelerating.
Didn't have the distance in the straights to get above 120mph. but I tried. Can't comment on speed limiter yet.
Bottom line is that the TRE gives more torque/HP down low and that needs to be managed in marginal traction situations. However that is offset by the power being more predictable and linear in its delivery. I like the more agressive but predictable power personally.
Nothing could catch my ride in the straights and I pulled on everything in front of me. This bike ROCKS.