I too am going to make an assumption that we're talking about a 3D foamy......Hey we're in the 3D Electric Flying forum..... Anyhow, the Park 370 would be the best bet, but with the higher Kv of 5400, a higher gear ratio will be needed. 6.5:1 would be a better starting point with an11X7SF prop, but a watt meter should be used to determine whether you're over amping anything, and will help in determining which prop to use..