TT and Magnum hard to tune and have loose parts? Huh? Not in mine and countless other's experience thought it is always wise to retorque all screws after the first several flights and to check screw torques before first flight-common sense.

Personally, I don't think OS engines are worth the money anymore because there are many other brands of engines that are equal in performance and cost much less:

Examples:

Irvine engines: true chrome
TT .46: cheaper than OS, never had liner problem
MDS .58/.68 if you need something larger, true chrome and absolutely reliable: Warning not idiot proof like OS line.
Magnum XLS is a good engine line.
Leo .46 (mecoa .46/megatech.46) slightly lower on power but 100% bulletproof engine. can be bought for 69 or less with tradein on several sites.