Tower engines are USUALLY very powerful engines. As you have noticed though, QC does need some attention.

The PRIMARY problem with Tower engines are air leaks. The backplate and carb are quite common. The other airleak (shows up on about 75%+ of the engines ) is through the front bearing. When you try to shut the engine down with the transmitter, the engine continues to run for 30 - 45 seconds (or longer ).

So far it sounds like you have one of the good ones.