Yeah, I've been thinking about this too, and I have an idea. Basically, have a wide mouthed barrel, and a very wide air nozzle. Then have this barrel taper down to a 6.01/6.03/whatever. This would get the air out of the cylinder, and into the barrel quicker. Even though the barrel does taper down, it would still push more air out of the cylinder faster, because usually the nozzles are somewhere around 4-5mm instead of the full 6mm. If you need it, I could draw something up.