To get the best efficiency and maximum output the mod and batteries can handle, MXJO batteries are re-wraps so treat them as low grade 20amp CDR batteries, about 55watts per battery, so maximum watts 165watts, in the future look to buying some authentic name brands from LG, Samsung, or Sony. Next is the sweet spot for maximum watts on that RX200, on my Sigelei 150watt as an example, though it can handle a 0.10ohm coil, to reach 150watts safely and efficiently the sweet spot is 0.18 to 0.32ohms I have found through trial and error, 0.10 or close to it just doesn't sustain as well as a 0.25ohm coil does on charge even though the voltage needed is much lower, being you have 9.6v available at lowest battery charge, maybe a 0.35 to 0.55ohm would be the sweet spot on the RX200. Also I'd suggest looking at 26 and 24awg wire over thicker 22 or 20awg, claptons, fused claptons I'd look at 26awg cores thickest and 36 to 40awg wrapping wire for the coils.