Any inline watt meter will work. It goes between the lipo and the esc. Trinity sells one and Hobbyking has one really cheap.The MMS is good to if you want to spend the money. When you do the test you want to make sure the battery is fully charged. Also make sure to remove your rear wheels. Then turn on your esc and give it full throttle to see where it peaks at. Usually 10 amps is where you want to be then adjust your gearing for temps.