The best Thunder tiger engines are the 46 two stroke and the 91 four stroke. There are nicer 61's than the Thunder Tiger 61 that weigh a lot less.

But 61's seem to be a thing of the past anyway. No one talks of them on here anymore. OS came out with a 91 that's in the same case as their 61. Magnum/ASP came out with a new 91 that's in a case that looks just like the OS 61 engine. Super Tiger has a G90 that's in the same case as their G61. There's also a new Webra 91 that's in a small case. As well, there may be others?

Enjoy,

Jim