I've tried the 13-4W first and 14-4W second on a new FuntanaS and have too few flights on the 14-4W to tell the difference (4-5). They both work great actually. The 13-4W does rev higher, but with 30% nitro at sea level, the 14-4W rev's pretty high too. I need more time to experiment with both. I finally bought a good tach so the truth will be revealed about my setup next time I fly. BTW, I rarely have either prop at WOT, plenty O' torque.