Hi, I just got everything back from Thumper Racing after alomst 3 weeks. Open up the box and check for everything: cylinder looks good, clutch springs, new plug and oil filter, all the right gaskets but when I opened up the piston I knew something was off... The part number for the piston is 9887M10241, says "Thumper Honda XR600 Dished-102.4mm." I went on their site b/c this does not look like a 10.25:1 compression piston, hell the stock piston is a flat top pretty much, this one has a pretty big dish. I tried calling TR but they closed down the phones early so I left them a message. This is what a was dreading, having the engine apart for this long and something like this happen, I still dont know for sure about the piston's CR b/c I cant even find it on Wiseco's website . Also, I put the piston in the cylinder to see how close the fit was gonna be and the was some play! Its a full floating piston (if that changes anything) and it just feels too loose from what ive seen in terms of specs. I should measure everything before I start frekin' out... Just one more thing, which way does the piston go in? There is nothing where it says Intake side or Exhaust side or does it not matter? For the piston rings, I am assuming that the black ring is the 2nd compression ring and the top is the one with the copper/chrome ring around it. There is no markings to which way the rings go either, usually ther is something so you put them in with a marking upwards or something... So if anyone has any info on this piston I got from TR and if this is the 10.25:1 (dont see how) or not, PLEASE let me know! Thanks a Million!! Zack Z.