I would strongly suggest Z Sails in Stamford CT. They have made sails for me and I know they have made sails for people at
CPYC which will be hosting the J/30 North Americans this summer. It is an owner operated loft run by three guys who personally design and build the sails, and actively race. They campaign J24's at the world class level. Great service, great advice and competitive prices. Get in touch with Chris Wentz at Z Sails, 203 353 8818.