For what it's worth, my Rave's T-foils on the outer hulls are optimal at 3 deg.

The angle of incidence is critical. A little incidence goes a long way but the best way to find out is by trial and error. You can get an angle meter at Home Depot or "Angle Finder" (same thing) at Ace Hardware for about $20 that is accurate for setup.

I think you will find that a little incidence and the extra foil area makes a big difference in drag in light air but is well worth it once the wind picks up.