With a 4 pound AUW go with the webra. I finally stepped up and bought one of these fine german engines. And this is when they costed $149 dollars. Now that they are $129 I have to say why not. Webras are great engines that last pretty well when treated correctly. Also a complete ABN set for rebuild is only 57.00 at Horizon Hobby. One thing you will notice when trying to do 3D is that instant throttle response is a must. The .46 size engines just did not have the quick throttle response with the large funfly props like the 50 size does. I have my Webra 50 on a Morris TopCap ARF in the 4 pound range and this combo makes for a great flyer with unlimited capability. Also avoid using a tuned pipe for 3D style flying. You want to use the torque of the engine instead for small corrections. Mufflers like the Ultrathrust and Tower Muffler are ok though.