Success! I rode mine to the park with my daughter today. We had a good time. The air-swirler I made from a computer fan, jammed into the rubber boot over the velocity stack, worked really well. The intake was a little quieter, and it pulled hard. I'll try to get a picture later.
I found one of these in the trash, and trimmed down the blades a little to fit. They break easily! It took me 2 tries to make one.