About $700. and 1/4 knot in boatspeed - {;>) Just kidding - I don't think there are many 'fathead M-15' mainsails on standard rigs to provide a realistic comparison - BUT you would have: a new sail (probably faster) 'Fashion forward' style points (actually more than that) your biggest gains would be on offwind/downwind legs - - go with the used main and see what develops from there. then go for the bitchin wahoo carbon load path model! (just kiddin' again) Sometimes these "modifications" backfire - folks seem to think a modified "part/rig/sail" MUST make you go faster or higher when all they really are is 'different'. Some are even a disadvantage - but the perception is 'hot rod' - develop skills then develop machinery is a good path. Time in the boat is worth more than almost anything (except new good sails ;>) Have Fun, Go Sailing. GO _www.wrinkleboat.webs.com_ (http://www.wrinkleboat.webs.com) In a message dated 10/24/2013 1:28:57 P.M. US Mountain Standard Time, griemmolo2@gmail.com writes: Wrinkle Boat Mates Am in the process of buying used standard sail from Daniel (Have you heard anything from Judy B/Hyde yet about your new sails?) Was wondering What the difference in the Main SA is between a standard Main and a Fatheaded Main. As I sail on a inland lake in NWI I have found that I am in light air most of the season. Much different than Lake Michigan my previous sailing venue with my Pearson 23.