Good one. I think you should contact your local sail maker and make sure to ask for the performance guarantee
As per all sail makers, they all offer a "first mark " guarentee which I would guess once you reach the first mark ( upwind of course ) the guarentee runs out.
More seriously if you trawl the internet there are plenty of main tuning guides written by some pretty good sailors, haven't yet found a similar assymetric spinnaker guide. <img src="http://www.catsailor.com/forums/images/graemlins/cool.gif" alt="" />
Scooby, the spinnaker is a GP same as your one.
