They're just a Magnum with a different label. There are several other 'brands' that come from the "Magnum factory" in China. It looks like some countries get one brand, and other countries get another. I suspect that "Magnum" is a brand that is copyrighted by Hobby People, so we get those. There's probably an agreement not to sell the other brands through different importers in the USA, but I'd think it'd be hard to prove. England and Australia get ASP's, and some ASP's come here from Just Engines, or at least mine (1) did, via way of SSW. While Magnum had dropped the XL .40 > .53, they were available longer from ASP, using up the stocks of castings...or boxes, or whatever it was they had on hand.
As a sport engine or stunt engine, they're nice stuff. The bearings and cranks don't like real high rpm. Those seem to be the first thing to go, anyway. I've never heard of a rod or piston breaking, but with a better crank and bearings, I'm sure that could be accomplished.

Steve