ORIGINAL: jefflangton Thunder Tiger also makes a great engine at good prices. Ive heard from more than one reliable source that thunder tiger engines are designed by a former OS engineer. I'm not claiming that, but after running several of them it wouldn't surprise me at all.
I remember reading the same from one of the model magazines, possibly Model Aviation. I think they also made the Magnum series. Thunder Tiger is a company in Taiwan. I've got a Magnum .15 and GP-07, and IMO quality is on par with OS. But I agree with the consensus that one is safe to buy OS, even though it costs a touch more. I have a number of OS engines going back to the 1960's. They have always been easy to start, fault tolerant. OTOH, I have a few other makes and models of engines that are cantankerous. OS is a safe bet.