Put larger grommets in the tramp to keep the friction from building up where the kite halyard runs through it. We just retro'd to #7 grommets and running it under the tramp works like a champ. The stock grommets on the C2 are WAY too small for the line to run smoothly, I think they are #2 or #3...

We've been through three different types of line and have settled (back to) on 6mm FSE Dinghy Control. It wears well, strips well, and seems to twist/tangle less than the others.