The O.S. Max .55 AX is very highly regarded. It's not inexpensive, but it is a good combination of power and ease-of-use.

RC Ken just reviewed the JBA .56 2-stroke available from:

http://www.kangkeusa.com
http://bj-model-engines.com/jba.html
http://knoxhobbies.com/

The JBA .56 has been tested by a number of reviewers, and offers similar power and ease-of-use at about half the price. The JBA .56 sells for $79.99 plus s&h from the three e-tailers listed above whereas the O.S. .55 AX is $159.99 at Tower Hobbies before applicable discounts.

The O.S. .55 AX offers better warranty coverage than the JBA .56, and parts availability will likely be better. If you spend the extra money to get the O.S. Max .55 AX, you will undoubtedly be happy with the engine. I own a JBA .56 myself, and I am very happy with my JBA.

For more information about the JBA .56 2-stroke with dual ball bearings and twin needle carburetor, check the following reviews and threads:

http://www.rcuniverse.com/magazine/a...rticle_id=1194

http://www.rcuniverse.com/forum/m_67..._1/key_/tm.htm

http://www.rcgroups.com/forums/showthread.php?t=603739

Other popular engines in the "souped-up .46" range include the K&B Screamin' .48, the Aviastar .53, the VMax .52, the Magnum XLS .52A, The Super Tigre G-51 ringed, the Enya SS50 Ring and Enya 50CX, and the Webra 50 P5 GT and 55 P5 GT, to name a few. O.S. Max didn't invent the ".46 Plus" category of 2-stroke, but their offering is a fine one. I'd be happy to own and fly any of the engines I've listed here.