Well, at first I thought it was a big waste of money because I couldn't feel any difference. After a few days or so, I started to notice that the first few gears were a lot smoother. I would take my girlfriend around and she commented that the bike feels much smoother than before. And for some reason, I dont know if this is directly connected or not but my bike does not have a problem starting anymore when it sits in the sun for too long. California models are known to have a minor problem starting in the sun due to emission standards. I no longer have to deal with that. My buddy also had that problem with his 04 gsxr and when he added the TRE in, the problem went away. He noticed the same results as mine, a smoother first few gears. So far, I love the mod and would definitely recommend it. I haven't had any problems yet. You might not notice a world of a difference, if any at all. So dont expect too much. How much are you getting the TRE for?