Sorry I can´t help you with the smoke, but want to congratulate you, you have bought a fantastic plane. Powered with that OS 4 stroke will do everything. I have it since end of august and have done more than a hundred flights.

Unfortunately I did not use a 91 4 stroke, but a 60 2 stroke, although powerful moves a 12x8 and the 91 would move a 14x8, with that, verticals should be unlimited. In fact I am thinking in buying another one to put there a 91.

Lots of luck with your show and your plane, the "chippy" will not dissapoint you at all. Hope you find a good smoke system.

Regards, from Spain