Had the TRE on a 2003 GSXR750, and 600 didn't notice any difference. Have it currently on both of my 2003 GSXR1000s and it's a noticeable difference especially in the mid-range, the power delivery is smoother which makes first gear useable now compared to 1st being very twitchy without the TRE. There is also less engine braking with the TRE which is great for the track.