Have both the Thunder tiger pro and the FX. Both engines scream after breaking them in. My thunder tiger was actually easier and faster to break in than the FX. I like them both. I would likely have two thunder tigers if I had the kowledge I have now before I purchased both. $40 bucks would pay for nearly three gallons of glow fuel where I live and that is a lot of flying with 46 size engines. Hindsight is ALWAYS so much better.

Just my opinion.

Eric