I have a good running 550xp, I believe it is a 2012 model with 3 piece clutch. I bought it used for $375 in 2015 and have used it seasonally since. It was more used than I was led to believe, but not beat up. Photos attached of condition when I bought it. How can I tell if it needs a top end? Do you normally replace them at a given interval or run them until the compression is low and hard to start? I haven't worn one out yet to know if they last until there is a catastrophic failure, or if the compression does fade over time. It could be a little down on power since I got it but it's hard to say for sure. I see Husqvarna OEM top end kits (cyl, piston, ring, clips, wrist pin bearing) are only $113 for the 550xp. Are the cylinders nikasil plated or matched to the piston? If so, I could get a OEM piston kit only for $55. I've never used the decomp button, is that a sign it needs a top end? Thanks.