Regarding the difference in the Evo and the Magnum, I have several different .46-.52 size engines, including an Evo .46 and a couple of Magnum .52s, and from what I can tell, the Evo must be made by the same people who make the Magnum. The carbs and the remote needle assembly appear to be the same, as does the general casting of the engine. That's what makes me think they were made in the same factory.

I could be wrong, but here is how I have it figured out.

I think there are probably 3 RC engine factories in China. One makes the Magnum for Hobby people in the US, the ASPs for the rest of the world, The SC (Super champ) engines and now, I think, the Evolution engines for Horizon. Maybe more.

Another makes GMS and probably the Tower and Aqua Craft engines, the Aqua Craft .46 being the Tower .46 with an aqua color anodized head and thrust washer for air boats. My GMS .47 and Tower .46 look a lot alike.

The 3rd factory makes Tiger Shark, the new SK engine for Kangke and probably the J'En .56 for Just Engines in the UK.