It is a common misconception that HVLP guns use less air than a conventional gun, it ain't necessarily so. The articles I have read on HVLP guns actually say they can use more air. HVLP means high volume low pressure. The low pressure refers to the pressure at the cap, not the inlet pressure of the gun, which can be as high as 50psi.
I just completed spraying the hood of my truck with my Harbor Freight HVLP gum. The gun did fine with the base coat, but absolutely refuse to move the clear with any kind of acceptable results. I eventually used my Binks conventional gun for the clear.