I am very familiar with the plane. The guy I fly with has one with a Saito 125 four stroke. It is his favorite plane. But part of the secret is its lightness versus the wing area and power. You will destroy this with a smoke system's weight. He had a OS 91FX on it then a Saito 100 and eventually changed to the 125.

Farther more, the exhaust temperature of a OS 91FX is marginal to make smoke. It will make smoke but not like you have seen the bigger planes do. There is not going to be giant clouds of smoke drifting away from your vertical hover. You will even be unlikely to get it to hover with the added weight of the smoke system. It will make a little smoke however.