25% is a lot of nitro for a 2-stroke. While it may be possible to tune that engine for that amount of nitro, it's just not necessary and a waste of $$$. Try 10% or 15% at the most. Your flame outs may be from over heating due to the high nitro or they may be simply due to the engine not being tuned correctly. Those engines are supposed to be tuned right out of the box but I don't see how they could be pre-tuned to run on anything from 10% to 30% nitro without adjusting the needles. There could be several other reasons for the flame outs, but at any rate, drop the nitro content and go from there.