Making it a combo will make it cheaper for them to sell. Also, maybe it is not quite a Neu motor, as in, like a cheaper 'can' it is built into?
“The modern astrophysical concept that ascribes the sun’s energy to thermonuclear reactions deep in the solar interior is contradicted by nearly every observable aspect of the sun.” —Ralph E. Juergens
Castle obtained rights from Neu to build a copy of the motor based on its design. It will most likely not be AS good as a neu, but I am sure that it will be a great performing motor and a big step up from a feigao. And you can't beat the price, around $300 is a killer deal. Its almost the same price as a 125b quark, and you get a motor too!