Well, I have a 1997 YZ 250 and feel it's time for an upgrade, probably to the YZf450. I was just wondering how the 2006 valves and such are holding up, and about how much in maintanence cost you'll spend on average in a year. I want a 450 hella bad, but if I have to replace the engine every year... it might be the 2006 YZ smoker for me. So, comments? Thanks!