With regards to "lowering the pressure", it's a question of what pressure you're trying to get to. I couldn't get above 250 fps w/ an 800 PSI feed. The gun should operate down to the 600 psi range if set-up right. If you're trying to get low pressure in terms of 200-400 PSI, then the laws of physics require the LPK. It's all about energy. A small amount of gas at high pressure has the same energy as a larger volume of gas at lower pressure. Granted this is a highly simplified explanation, but it's related to the simple work equation: W=F*d, where W= work (energy), F= force (pressure differential across the 2 sides of the paintball, and d=distance, how long the force acts on the paintball (as it travels down the barrel of the marker). With the LPK you need a sustained, say 300 PSI all the way down the barrel to get the energy imparted to the paintball to get the velocity up (F=ma and then v=1/2at^2). With higher pressure the actual energy imparted to the paintball changes as it travels down the barrel due to the dropping of pressure behind the paintball.

This simple principal is why you don't get more shots per tank with LPK, other than utilizing the lower end of the pressure range in the tank.