Since Metallizer is a lacquer-based product, adding an enamel would result in a paint incompatibility, and the resultant mess would probably be not to your liking. In addition, Metallizers use actual metal particulates as the primary pigment suspended in a solvent vehicle, while most other lacquers/enamels use a colored pigment made from titanium dioxide (There are many exceptions to this, of course.) Just my opinion, but I don't think Metallizers would mix well with other lacquers, either.
But, hey, what do I know? Try it and see what happens (lacquer/lacquer, not lacquer/enamel.)
BTW, you should be able to mix two metalllizers together without much problem. You could try a titanium/exhaust/gunmetal in your aluminum and see if that knocks it down a few shades.
Gip Winecoff