The little bit of soot that is on the inside is because I haven`t yet polished them this spring. Working in steps here. They clean and shine easy enough. It just has fine scratches from polishing. They are are pretty much straight lines. I`ve been using muggier`s mag polish on them, but that seems to leave polishing scratches in the direction that I polish. This is the case on both the inside, and outside of the exhaust tips.
Well, if the product and/or the media you are using has caused those scratches, better think of another plan.
Is that a chrome tip ? I have cleaned zillions of these on all the marques, especially German marques, and never had an issue scratching them using the products and media above..
I always go gentle on chrome because you never know how thin the layer is..
Are you able to replace those tips if they react badly ?
If you can, then I would experiment on them (only since its your own car), and see what happens with other products...
I know the Optimum Metal Polish has abrasives and chemicals in it and you need to really shake it up before use and during use..
On the looks like stainless tips on my TL Type-S, it cleans them really nice but does not give me the pop I want, so that is why I go over them after with Wenol Red tube and they come out beautiful..
Same with the 3" stainless tip on the back of my Grand Cherokee...
Dan F