Im pretty sure I will buy the 80" Edge 540 ARF with the OS 1.60, I see it comes without a muffler. my question is where do I buy either a good muffler or pipe and header for this engine? also thinking about using a 18x6w prop will the prop be ok to use? according to OS they reccomend the following props? Aerobatic: 15x12-14, 16x10-14, 16.5x10-13 Sport: 17x10-13, 18x10-12