Alot of the exhausts I've seen on mocern F1 cars don't show alot of colouring. They usually end up a dark chrome colour with a dull sort of shine. If they do show any colouring, they usually show a gold/brown colour with small areas of blue.
Try spraying a chrome paint, and then spraying a few very light coats of a gold/brown colour. Then maybe apply some areas of very thin clear blue over the bends and joins in the pipes. It's better to have the paint a bit too thin, because then you can slowly build the colour up til it looks good to you.
If you don't have an airbrush, you can try drybrushing the colours on. Again, build up the colours slowly for the best results.
Here's a good example of what I mean:
What car are you building? If you need any pics I might be able to help you out.
Hope this helps.