if you mean 250 spacer vs. 300 spacer I think they are the same. If you mean adding a spacer to a 250, well... I have a '00 and '04 in my stable (both 250's). The '00 never had a spacer, the '04 always has. But I can't really compare for you. The '04 has heavy flywheel vs light one. Also has GG pipe vs Gnarly on the '00. But all having been said, these are 2 absolutely differant bikes. The '00 is a real fire-snorter and is ready to pick the front end up at the flick of the wrist. The '04 is so mellow you would think it was a step-child to the other but it still has all the power, just kind of blends. Maybe someone else has tried their bike with and without the spacer and can chime in. I can't imagine it would make that big of a differance all by itself but I may be wrong. I think I have read that a spacer will soften the powerband hit and promote better low-end response.