With an O.S. FX stock, you should have no problem getting over 120 mph with the predator. The tower muffler is cheap power, but the Ultrathrust or Jett mufflers will give it a little more juice.

As too props, if you go with the stock muffler, the pylon props in the 8.8x8.75 up to 8.8x9.25 seem to work best for top speed.