Hi!
They are Chinese made!
SK , ASP, Kyosho, SC are all very good engines. All are ABC engines and all produce good power, some in fact are more powerfull than the same size OS engine (ASP/Kyosho.40-.46).

The Kyosho .40 GX turns a 10x6 RAM at around 14000rpm. The SK .40 turns the same prop at 13700rpm using 80/20 fuel and both engines have instant throttle respons and are very reliable.