There is a guy out of Wi. on E-bay that has very good deals on spi coated pistons, I've bought enough from him I should remember his business name, but I don't! He was $150 for a set of pistons and rings for a 900, 800's were a little less. I don't remember for sure but I think he is the same guy I got complete gasket sets from too. The reason I usually go though Millennium for cylinders is that they usually have exchange units. It doesn't cost anymore and you get a cylinder in just a few days. They are out of Plymouth Wi.
