This design will have engine sounds (not the best in the world but no worse than HL i wouldnt say) digitally created on board and all the gun and track sounds etc. will be on the same external SD card board that bills battle unit uses now. Neutral engine revving is actually harder than it seems it would be to do. Its dificult to get it to sound correct revving the unit up quickly, but I have enlisted a friend of mine to help me develop on an STM8S-Discovery board. I told him if he helped me get up to speed on the Cosmic C compiler id help him tune the software on his quadcopter. so we will see.