One of the problems with high metalic is you can sometimes with a blotchy or modeling effect after the paint is on. This happens when you put on wet coats and the metalic isn't applied in a uniform way. What we always did then, was turn the material down and the air pressure up a little and go back over the whole car with a uniform coat; keeping the gun at the same angle the whole time.

After you get the base looking good, then go back over it with the clear.