I have a Super Tigre G-61 Ring engine I bought new from Tower a couple of years ago. It's on my Sig King Kobra and it's a wonderful engine. It's powerful, reliable, it starts easily, and it's only getting better and better (more power, less fuel consumption) as I continue to run it.

I do have two pieces of advice:

1) The engine will come with a gasket for the exhaust header - you should throw this away and bolt the exhaust header directly to the crank case. The gaskets fail every few flights and aren't needed in the first place.

2) Use thread lock on the exhaust header and muffler bolts and then double-nut them.

Keeping the exhaust bolted up to the engine has been my only issue, and it's easy enough to do if you follow my advice above. I also have an old ST Bull Ring .46 engine that runs like a really powerful Swiss watch. I will happily buy more Super Tigre engines in the future.