Any spinnaker using a fixed pole is by definition an assymetrical spinnaker as it has a designated tack and clew. A symmetrical spinnaker uses a spinnaker pole that moves from one side to the other on jibes while the corners take turns being the tack and the clew. When the sail is folded vertically the clews and leeches match each other in length and location. When an assymetrical is folded vertically, the luff is shorter than the leech and the corners do not match shape or location.

You want a larger, fuller cut A sail for the Wave in 1/2 oz nylon. Yes, it will make the Wave faster downwind than stock up to the time it pitchpoles. There is very little bow in front of the main and with the spinnaker the sail plan center will probably be about even with the bows. My opinion is that this will never be worth doing unless you already have the snuffer and sail and you would use it often. Buying the parts retail might double the cost of the Wave.