I just recieved this plane from my mother for Christmas. I also recieved the Sullivan smoke pump (electronic). Was thinking of putting it in the UCD. Anybody done this? Is it going to add too much weight? It's going to be powered with a Magnum .91 four-stroke.

The more weight you put in it, the less performance you will get out of it, regardless of the engine size. You might want to save the smoke pump for another day.