It was only when I saw this photo I took of Zoltan Veres spinning his Extra 300 in full size on my computer screen that I realised the small bright spots thrown off from the main smoke cloud are little smoke rings. I’ve never seen anything like that before. Here are two crops from the full-sized image that show the rings more clearly.
Zoltan Veres is an amazingly talented pilot; take a look at these videos I found while looking up info on him.
craniac's place 
smoke rings!! they are so cute and perfect, hehe *putt putt* dig the shots, well done you
Great shot, Steve!
Those are some insane acrobatics – really impressive, especially since done at such low altitudes – definitely a talented pilot indeed.