If I remember, Rashman used very fine wet and dry on his and they came up like new, I remember seeing them at one of the meets and even a clean freak like me was unbelievably surprised. Then he used a cutting compound, cant remember the exact name of it, but I used 3M cutting compound and that alone was brilliant and bought mine up to looking new again.
Have a word with the Rashman.
I too have used very fine wet and dry paper on the insides of the exhaust on my CLK. It really does work..
Im going to have a go at them again next time with some 3M compound and more wet and dry after hearing that