Just thought I would let you guys know that I put a piston and rings in my 06 450f. It had a total of 50 hours on it when I did it last week. Everything looked pretty good inside after 50 hours,the cam chain looked good,valves were in good condition but they did have alot of carbon built up on them along with the piston so I just scraped all the carbon off the valves and had to re shim them (only one size) The piston and rings looked good also but since I was in there I went ahead and replaced them also The cams were in execellent shape. I guess the 06 will hopefully be good for another 50 hours..... Your do you guys think I should stretch it to 60 hours next time?