Exhausted

I was wondering if anyone could help me with something I have been trying to find out. I have noticed that a lot of you do really nice "weathering" or "heat treating" on exhaust systems. I have spent a lot of time trying to find a good tutorial on a way to get these effects but havent found any. Does anyone know where I might find one or could someone make one. I was also wondering if you could also tell me where to put proper colors in proper locations.
Thank you for any help you can give.

Here is a picture as to what I am referring to, but I am thinking for a automotive exhaust system though.


http://img93.imageshack.us/img93/1364/alclad11newswatcheshotm.jpg

:wave:

The best way to determine proper location and proper colors is by looking at pics of exhausts- preferably pics of the system you're trying to replicate.

I like to use clear acrylic paints sprayed over metallic colors. My technique looks a bit like this (http://www.automotiveforums.com/vbulletin/showpost.php?p=3320371&postcount=73).