The smoke generator was the surprise that I promised earlier :-)
It works quite well as you can see on the video above. I mounted it so that the output is at the same location as the exhaust on the original CAT 390 F.
Ebay link:
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http://www.ebay.com/itm/112036055150
I have the 12V, "standard NON ESC" version with red color. I control the variable output with the first channel on the fourth motor controller.