Do you sail with iSonics ? I sail my iSonics with SL7 and i don't like them. Only when i am overpowered the fin feels good. With less wind the board feels dead and sticks to the water. I sail the masttrack behind the middle position.
isonic 133 wit RS7 49 with vapor 8.2
iSonic 101 with SL7 39 with vapor 7.6