They are a great selling point on HL tanks. People love them. Serious RC tankers remove them to save room and battery power. With the dawn of Lipo batts and high capacity 7.2 stick batteries that is not much of a concern anymore. A working exhaust smoker is neat especially if it is proportional. We had several tanks with smokers at Danville at the 2011 Extravaganza. It was very realistic seeing them bellow smoke out their exhausts. My buddy Phil Pfleuger sold a bunch of them and installed a few at the Danville event. IT wook me a year into talking him into coming to VA. Sadly, he passed away but his legacy goes on with the many quality tanks he created. If I had my wish come true, I would have the knocked out tanks stream and spew smoke continuously from the engine when the get knocked out in battle, like the real thing does. My next wish would be a realistic smoking gun....