Thought I'd stick this in here, rather than in Jayjay's profile thread.
I mentioned to him about getting a wire wheel to tidy up his exhaust systems flanges. Well I thought I'd show you all what can be done with a little elbow grease…
While systems are stainless steel, they will never last a lifetime on our roads, and do corrode! There are obviously some grades of stainless steel which help the situation. As for mild steel, that goes without saying, you will need to clean up a lot or protect with exhaust paint.
I bought one of these, altough annoyingly paid a lot more than that!

http://www.drapertoolbox.co.uk/draper-w ... 4334-62633
Pretty simple how too, to be honest:
1) Using a drill and the above attachment, go to town on the worn, deteriated exhaust.
2) Final step to smooth the wire scratches a little and add some protection is to use a metal polish of some sort - I use Autosol.
Here are the results you can get (shown on a decat) :
BEFORE:

AFTER:

BEFORE:

AFTER:

FINAL PRODUCT

Here is an example of a manifold I started, shows the differences quite well - just wire wheel, no polish yet:

I'll update this thread with finished pictures of this one. /\
For VERY pitted steel, a wire wheel will only get you so far, then it's down to how far you want to grind the metal making a thinner exhaust wall. I would personally recommend getting as much off as possible with the wire wheel and then adding an additive like Kurust (or other similar products), to convert the corroded parts into a tougher metal (don't ask me what - science was never my strong point!).
That's it - random how to, but mainly to show what can be done.

Cheers,
Rob