i dont have money for another board, so i wanted to get a good pair of fins. Dimensions on my board are 6 4 x 19 3/8 x 2 1/4, its a big wave, big guy board, and im not surfing anything over 8 ft and i only weigh 170. i wanted to make it more maneuverable/looser. Any ideas? I was thinking of making it a twin fin setup on smaller days to make it more slidey, is that a good idea? Any answers would be appreciated!!