I tried a bunch too and think the Mezjlik 18x8 is the best. Pro Zinger 18x8 turned much faster but didn't have as much thrust. Are you running a pump? 5 of us at the field have pumped 160's and are running the mezjlik and all get a consistant 8500 on the ground. Pro Z 18x8- 9000. Reg Z 18x8- 8000. Large APC's have a smaller area and not as much load on the engine. I don't know why, maybe to make their numbers look good. Anyway, they are more for speed instead of thrust.