to me rebuilding is pointless, i mean for a high end engine its not, but for the RTR engines i dont worry bout it, the TTR28 is a dam good engine though, i love mine, but for the price of a rebuild kit, i would proly just get a brand new TTR28 of ebay for cheap, then i have a spare parts engine for about the same price as a rebuild would of cost. But yeah il proly just re pinch it and have it as a spare if my STS28 dies for some reason, Piston and sleeve for the STS28 is only like 30 US [X(]