Hi Louis
Thanks for the email and fast 3 day shipping. Sorry my  short voicemail was rambling and incoherent when I called you after sailing  the 10x 15 combo on 83 quad with 5.0 but I think you understood how Impressed and happy I am with your engineering prowess and expertise. Your spot on for a 190lb guy like me living in Maui  over five years and sailing  twins and  quads  almost everyday  in rough and choppy swell and waves in Maui with your template,foil,flex pattern,fast G10 epoxy flex recovery response,low drag, higher top end speed,comfortable softening and dampening in chop and jump landings, point upwind and plane up well, never cavitate spin out or hum, much improved jibing , looseness and wave performance enabled by controlled flex and twist resulting in higher angles of attack and a slingshot or boomerang effect out of turns. I also like your small cutout at the base of the fin that loosens up the board and allows ( along with the flex and twist) easier controlled drifting or spinning the tail on tight outside jibes on a waveface. Your fins also maintain grip and control on a fast broadwind or downwind reach. I have owned and tested at least 5 fin brands in various sizes including customs in twins and quads. I have been surfing short boards and long boards for over fifty years and windsurfing over 30 years in San Diego,Baja and Hawaii and always appreciated  what an important and critical effect  specific fins and their placement make to performance and my enjoyment of  surfing and sailing. I will give you a call to order another quad set.
Thanks Jim