I just did that custom job on my Inter-17R Mainsheet, the change is breathtaking.

I'll post a pic and exact sheet names later.

What you do, basically, is choose a mainsheet with a spectra or vectran core, and 'pull away' the cover. The exposed core runs incredibly smooth in the pulleys. Also choose a sheet 'cover' that does not 'expand' or 'sponge' water in.

I'll post a pic. I was inspired by som.e canadian Olympic Tornados and 1 of the 18HT at our club that was bought from the Alter Cup.

Later