I First strip off the chrome plating, the paint does not stick to it as well. This also allows you to clean up any mold lines or glue joints. After thats done I spray the exhaust silver. Next I spray clear blue at very low psi with my AB to the areas I want to blue, usually up near the flanges and at bends. Then I spray a very small amount of clear red at the center of each blued area, this gives it a subtle hint of purple that fades into blue. Finally I spray a little bit of gold/silver, about 50/50 mix, on the edges of the blue. This has worked quite well for me.
Darren