Nico, I never used the "Acid bath" method but when i get mine polished, we sand blast it so all the power-coating or paint or little bumps come off, then we smooth out the surface then start polishing it.
What does Acid bath do? If you are trying to clean up the inside and out side for the grime, you can simply high pressure blast it and it will take all the old grime off...
This is always the way I did it, By the way, don't even think about polishing the intake with your simple hand tools and grinders etc etc,
You need the professional polishing tool to do this right, otherwise you will have flat spots if you polish one spot too much which is very easy to do,
I tried to do this myself with hand tools as well, it would have taken VERY VERY VERY long time to complete it and it will never look like the pro polished finish. Prep it and clean it, then take it to the shop to get it polished. That's the easiest way
