The TT Pro .46 is every bit as good of an engine as the O.S. Max .46 AX. Both are very user friendly, reliable, and easy to tune. The Thunder Tiger comes with a 3-year warranty instead of the O.S. Max's 2-year warranty, and will probably prove more durable in the long run. The O.S. Max .46 AX should have spare parts available from any hobby store on Earth, however, and in North America, the quality of service from Hobby Services (warranty provider for O.S. Max) is second to no one.

There are some very good engines available that would allow you to save money and provide "extra oompf" in the future if necessary. Ed Mooreman tested the JBA .56 available from Kangke USA for $79.99 and found that it was almost identical to the O.S. Max .55 AX in terms of power, weight, and usability. You can purchase the JBA .56 from http://www.kangkeusa.com or check them out at http://www.bj-model-engines.com/home.html A JBA engine isn't as nicely finished as an O.S. Max, nor is the warranty as good, but it's a hell of a good engine for the price.

You can read the whole thread here: http://www.rcuniverse.com/forum/m_67...tm.htm#6762745

The highlights include the following:

"Your engine has 5 break-in runs, plus 2 or 3 tanks for the rpm testing and 4 or 5 flights, I forget. It 1-flip started and never missed a beat in the air. I flew it with an APC 12.25-3.75 3D prop, Omega 10% castor blend fuel. I would say an 11-7 or 12-6 would be good props, too. The glow plug is a K&B that I had and nothing special. It didn’t come with one and this one lasted the whole time. I wouldn’t change any of the settings for the first flight. Oh, yes, I had a kill button set up on my JR 9303 and the engine shuts down after maybe a 1-3 second delay.

They both started by hand in usually 1 flip. The only time I used a starter was when I was doing the rpm runs and ran short runs to tune for max rpm, then shot down and changed props. The engine never got a chance to really cool down. I bumped it with a starter and it went right off.

To tell you the truth, I have looked for a down side and haven't found one. It just starts up, runs good and keeps on running. And it will definitely out turn any .46 out there. Maybe not a Jett on a small 10-6 prop, but probably would on a big one."

Several folks have been checking out the Aviatech .46 and Aviatech .53 2-strokes since they went on sale at http://www.sigmfg.com earlier this summer. You can try the .46 for $49.99 or move up to the .53 2-stroke for just $69.99. By most accounts, they require a little more work to break in and tune, but the folks who've purchased them have liked them.

There are lots of good choices on the market. I don't know anybody who has bought any of the O.S. Max AX-series engines and not been happy with them. It's really just a matter of budget and whether you want to try something different or stick with what you know.