Intake--Exhaust porcelain

Try to ge hold of a new bottle of NIGRIN's wheel activ cleaner Nano-line,
( the one that's first blue while application and turnes violet after reaction ) dab it generously in the rustspot and leave it for about 20 minuts, clear it of with lots of water, drye it thoroughly with a hotair gun or hairdryer and use either stoweennamell or heatrestitant paint immidiatley! I use it on rusty stonechiped carbodys for clearing of sufacerust bevore touching up the chiped part and prewenting furter rust and avoiding to sand the whole spot.
worked also on my ennamelled collectors too. <!-- s:wink: --><img src="{SMILIES_PATH}/icon_wink.gif" alt="" title="Wink" /><!-- s:wink: -->

I have intake- exhaust manifold off my x-brand car now, and I would like some info on how or what I could use to clean up the porcelain on it. The porcelain is original and in good shape. There is some minor rust spots on it, what could I use to clean this thing up and not damage any existing porcelain on the manifold?? Man what a mess this thing was on the inside of it. I just love those mice don't you guy's?? This was stored in a corn crib for about 12 years. Buy the way this thing came off real nice No problems. I had it off in 45 min. Removed from my in-line 8 Jordan.