As I promised, I was going to show some before and after pictures of the exhaust system. Before I do that, let me tell you what I used and how:
1. Remove excess dirt using Poorboy's waterless wash and microfiber towel.
2. Turtle Wax bug and tar remover via soft toothbrush, then bug sponge.
3. Removed excess film created by Bug and Tar remover with Poorboy's waterless wash.
4. Sonus Clay bar (the grey one) and Sonus "Glyde" clay lubricant.
5. Poorboy's Pro Polish applied with soft sponge (at this stage it is very difficult to really polish the metal because of the tight spacing...no true chrome polish was available at the time, it was all out).
6. Since Poorboy's didn't seem to improve anything by much, I tried Klasse All In One without much of an improvement (as expected since Pro Polish is supposed to be stronger than All In One).

Bottom line: I really don't feel like the look was improved that much, but maybe that's just my opinion. Super-duper small spots are still lingering, and I don't like the way the chrome tips came out. The car had about 10,000 miles since the tips were last cleaned, so probably so it would seem only natural to see some pitting. I'll have to get some more true chrome polish for that.

Here are the before pictures (please try to ignore my poor picture-taking skills):