skulboep: Some people like Super Tigers, but most of us don't. My personal experience includes two ST90s and both of them were terrible engines. They could not be made to run clean in the mid-range (even by the Super Tiger experts) and they vibrated so badly that one of them shook all 12 of the fuselage servo mounting screws loose in two flights. (Yes, the plane was a total loss.)

On the other hand, the OS 91FX is not one of OS's best. I'd suggest that you take a look at the Thunder Tiger Pro 91. Cheaper than the OS and gets good reports from it's owners. Stay away from the Magnum 91XLS. It is an exact copy of the OS and has the same problems. (Imagine that!)

Jim