You could also try putting a 1 1/2" long plug (1/4 or 5/16" dowel) in the bottom of the fin to see if it makes a difference -- either way I think it will be an improvement over standard fins. IMO, you won't get the full potential of the Turbos at the higher speeds, and they will eventually crack at the tip of the existing mast due to flexing (depending on how hard you use them). It's sure worth a try though!. I'm looking forward to your results!
PS. If you put a plug in one side (allowing about 1/4" gap for the fin to wind up) and try the Drive, you can test whether the plug helps. If the plug improves performance, that fin will have more thrust, making the boat rock slightly as you pedal. If the boat doesn't rock, then the plug probably didn't make a difference.
PSPS. I'm sure you realize that the V-2 fins attach to V-2 booms, so if you are changing from V-1 to V-2, presumably you got new booms with your fins.