Not bad, that is better than the Tower 75[X(] But what I wrote previously still applies, it will be faster with a 12-8, as long as it`s not a really draggy plane.
12-12 is just trying to kill the engine.

Sevans16. If you are this hungry for maximum speed you really should have bought the 91 FX instead. It will turn the same prop faster, or turn a bigger prop just as fast and it is basically almost the same engine when considering the weight and physical size.