The Magnum engines were made in Taiwan from the factory that made Thunder Tiger.
A story that I was told some years ago was that when the Taiwan company wanted to enter the market, the US distributor that they selected was concerned about possible confusion between Thunder Tiger and Super Tigre so they changed the brand to Magnum.
In Australia, I have seen both Magnum and Thunder Tiger and all the model names were the same.
About the time that Tower cleared the Tower 40, I found the company in Taiwan. It was actually a sewing machine manufacturer.
For an order of 1,000 units, they would make the 40 for anybody.