Hmmmmm
Ok pretty simple. A it is some hard or rather time consuming work. B it is easiest to remove the headers to do it.(Header is what he is talkin about) When removing be gentle as not to damage gaskets on head pipe. Also be gentle with header studs, WD40 and heat from a butane tourch work well to remove without damage.
Now the nitty gritty of it, you'll need to sticks of polishing compound. 1 black for cleaning surface rust and discolor and 1 green to buff to shine. Also needed 1 corded drill and two sisel pads.(pads for buffing) Use 1 pad for black compound and 1 for green. Put pipes in vice on shop table (Genlty now), start with bla,k compound. Apply sparingly and often to sisel wheel. Polish with the grain( up down length of pipe not across) once cleaned to your satisfaction,switch to green on new pad and buff.
Warning: Dirty job so be prepared,and takes time but you can make them look like factory new.
Ps wipe down pipes once re mounted to remove any oil,fingerprints ect as these will burn sots on pipes you just made perfect.