Oracus,
You can order a Sound Smoke upgrade kit for about $66.00 The upgrade will give much better speed control, main gun, MG and engine sound effects and of course smoke, however that usually stops working in a couple minutes anyway. The $66.00 is about half of what you'll pay for a new tank from the reputable sites, or about the price for a new tank from some of the other sites, but you may be taking a chance from ordering from them.

Jim