Definately try the Tamiya Thinner. They add a flow agent that really helps in the airbrushing department. Using alcohol sometimes leaves you with a grainy (orange peel) texture, becuase some of the paint drys up in mid-air before it hits the surface of your model.
I use a 3:1 paint:thinner ratio most of the time. (I try to acheive a milky consistency when thinning Tamiya paints for the airbrush)
This thread is from 2003!!! Why are you digging up this stuff? You are wasting forum members time every time you do this. I feel you know this, and continue to do this for whatever twisted reason you may have. I am asking you to stop.