With a MAS 12-6 prop ou should be able to get a touch over 12000 rpm. If you get the extra 1000 rpm over the 11000 you get now you will see a big difference in getting the plane up to take off speed. When I first bought my new tach I tached different engines on trainer planes to see what kind of rpms the props were turning with the different engines. What I found was that if the engine was turning a MAS 10-5 prop at 10,500 rpm on a 40 engine. The plane barely had enough speed to get airbourne. 11,000 was a bit better. 12,000 was quite good and was obtainable with engines such as the Super Tiger 42 size. At higher rpms (just over 14,000) such as you would expect to get out of a OS FX or AX engine the take off was short and fast! These take offs are all off a rough grass field. Hope this info helps. [8D]