ART makes the oem yamaha pistons & pro-X is a better piston than stock & is also the only piston & rings that are universal w/ the OEM's .......as far as the best pistons ... i would only run WIESCO...just did a rebuild & what did i use?? WIESCO the lightest & durable... on one of my motors i used ART (the OEM) & the where breaking apart!! literally !!! pieces of the pistons where breaking & bouncing around in the combustion chamber & fucked up my domes & lost compresion...bc they broke apart inbetween the 2 rings......only run wiesco.... try other then try wiesco .. u will never go back!!!!
there is my $00.02