The power you get depends on the blade diameter and the wind speed.
If you are in a low wind area you might get a little more if you modify the design to be at best efficiency in light winds. You could possibly come down a bit on cut in speed but you must be able to get the thing to still survive in high winds which you will get at some point.
You won't be able to reduce the cut in speed a great deal without running into stall even in the low winds. Prop tsr falls rapidly above cut in and if you make the cut in too slow this effect affects you in the useful 10 to 15 mph wind range. Unless you use some form of mppt you will probably gain very little by reducing the cut in below 7mph.
You can shift the working range up or down a bit to suit a high or low wind area but in the end the only way to get lots of power in low winds is by increasing prop diameter but you are then into unknown territory if you start modifying a standard design.
Flux