All the 880 kits (Split Second, Trygstad, Bikeman, etc) run the 86mm Crank Shop spec Wiesco pistons. They have to be ordered from Wiesco.....sometimes harder to get. The 860's run a variety of 85mm pistons and seem to be more readily available. If I was doing it again, I would send my stuff straight to Sled Head Racing (Big John). For 2000 bucks USD you get the overbore, nikasil, pistons, porting, Rave mod, AND RKT head. Plus his set-up instructions are usually VERY close. I had to send my Split Second 880 to him this summer to be re-done....I will NOT recommend the SS to anyone.