Dreaming of buttsecks for years...
Since I own one, I spend a lot of time in the 04-05 600/750 forum. I also see a lot of the same complaints over bikes lacking power up top. If you don't have an STVA code, this points to a fuel delivery problem. Most people want to do a pressure test, which isn't a bad thing, but the tools to do so aren't really cheap. The timed delivery test is one that you can do in your garage for less than $20. This test is super easy. In this example, I'm using my 2005 GSX-R600.