Actually, even that first idea you had would be pretty hard to pull off. Consider industrial air compressors. A 40 gallon compressor at 135 psi will bleed down to zero guage pressure in about 8 minutes of continuous use without the compressor working to counteract, and that's through a 1/2" ID hose. You're talking about feeding a 5x mm throttle body, with enough volume to produce positive manifold pressure while the engine is trying to pump air through itself anyways. I think I'll stick with turbos, they weigh less