Using three angles vs. one just makes a smoother transition into the cylinders slightly increasing flow. Therefore it will slightly increase you power output with or without the juice.
3 or 5 angle vob job is done to increase the flow. It allows it's transition to be smoother which allows it to produce more power. It's worth it with or without Funny gas. just my .02
cutting more angles in the valve and the seat, makes it a smoother turn. If you look at the stock seat, its just flat. a 3 angle will make the seat and valve have 3 angles i believe, a 5 angle, makes 5 angles which is better flow.