We're not familiar with the ouput of the Magnum engines, but a 1.20-size engine is 20cc of displacement. The US Engines are 35 cc and 41 cc. They will turn a much larger propeller and are also two-stroke instead of four-stroke engines, so they should put out a bit more power, but at lower RPM.

As a comparison, the O.S. Max FS-1209 Surpass w/o pump is rated at 1.9 Hp, while the US 35 cc is rated at 2.4 Hp, and the US 41 is rated at 3.0 Hp. Remember they are much larger engines in displacement. They also weigh about 4 pounds each, as opposed to about 2 pounds (w/muffler) for the typical 4-stroke 1.20.