we carry them and sell them along with the je pistons and wiseco. they are good pistons and we've had no issues with them. if we can help you with one let me know.
My sons have been racing amateur motocross using LA Sleeve/Niks Pro-X pistons for two years now and we have had very good performance and reliability. See the LA Sleeve vs. Crower Power comparison in MXA (Sep. 2007).