Ian I used the TPUSA HC pistons in my bike. I don't know that helps you much but if you wanted to get eyes on them there is a pic or two of them in my build thread.

SOLD: 07 Black BA, 39mm FCRs, TPUSA stage 1 head, TPUSA 813 cams, TPUSA 10.8:1 pistons, TTP #3 igniter, Specialty Spares Long Cannons, Tsukayu Hard Bags. 82HP/55tq NEW: 19 Goldwing Tour DCT