Found a tube of this in the garage today. Has anyone used it to clean pipes, etc. on their bike? Thought I'd ask before I applied.

It works well, I’ve used it a number of times with good results.
Clean part—apply small amount—rub until you see a glaze—let dry a few—rub off w/ soft cloth.  
On a muffler I’d work on 1/4 of the total surface at one time.  After applying 1 area, apply to another while the first dries, etc.
Using 2 fingers with an applicator (cloth/sponge), squeeze some out (about the size of 1-2 erasers on a pencil).