C
I have been testing a set of these new pistons and have been very impressed. The power fade issues inherent with the ski-doo twin are GONE. I installed the pistons feb 2011 and I have put 1269 miles on the machine since with no issues. Dollar for dollar you can get a better than stock product with these pistons. If its time to freshen up your 600ho give these a shot, you wont be disappointed.