A copper penny. Doesn't scratch and takes it right off.

 

Mr. clean magic eraser, it took the wifes heal off my exhaust with no scratches.

 

Make sure you don't spray the oven cleaner directly on the pipe. Put it on a rag and wipe it onto the pipe. Overspray will make a real mess. Oven cleaner works well. Leave it on for a couple of hours and stain will wipe right off.

 

Ez Off COLD oven cleaner.

 

Steel wool and brillo pads seem like they would scratch the chrome to me. Ive heard the penny works but it has to be a pre 1984 penny from what I hear because of the copper content. Never tried the easy off either but that sounds good if it doesnt require abrasively scrubbing the chrome.

 

Tell the wife to be more careful! LOL

 

Thanks guys for all the tips!

E-Z Off cold sounds like it is worth a try.