the lighter the better. I don't normally fly foam, but I do have a tensor. 4.4 gram servos, gws 4ch rx, hacker A20 34S and 2-cell 480 pack, just a few grams over 7 oz. Flew it with the 28M hacker which is a half ounce heavier, with larger 3 cell pack, at a little over 9 oz, and although power is higher of course, the plane flies far superior with 20% less weight and a little less power.