Looks like a fairly sophisticated version. It should have both gasoline and nitrous nozzles.

For a simple 'fogger' (simple spray into air cleaner) I would guess more like 10-15 HP would be plenty for a stock engine (which are only 35 rwhp anyways). Otherwise you might need a extra fuel delivery. The stock engine should handle 25 hp easy if you get enough gasoline into it. A12s are fairly tough right out of the factory.