I used Simichrome blue away, #0000 Steel wool and a polishing rag and it worked GREAT to get the spotting and blue off! Maybe even TOO great haha. If you like the bronze color on the pipes then I don't recommend trying to get the spotting and bluing off (I think it doesn't look bad and almost liked them, I know some on UK forum like having the bluing because it shows they ride the bike hard) . I had quite a bit of spotting on mine and don't mind losing the bronze color. I'm taking a break and haven't decided if I want to do the bottom portion of the pipes or leave that part bronze.
Here are some before and after pics.
[url=http://s1329.photobucket.com/user/red_VIII/media/photo1_zps45654e48.jpg.html]
[url=http://s1329.photobucket.com/user/red_VIII/media/photo2_zpsb058c19b.jpg.html]
[url=http://s1329.photobucket.com/user/red_VIII/media/photo3_zps5382f5af.jpg.html]
[url=http://s1329.photobucket.com/user/red_VIII/media/photo4_zps1c0801c9.jpg.html]
[url=http://s1329.photobucket.com/user/red_VIII/media/photo5_zps30754d6d.jpg.html]
[url=http://s1329.photobucket.com/user/red_VIII/media/photo6_zpsd37c5638.jpg.html]
[url=http://s1329.photobucket.com/user/red_VIII/media/photo7_zps91f86806.jpg.html]
You can really tell the loss of bronze in these next two. The pipe on the far left wasn't that bad and I saved for last.
[url=http://s1329.photobucket.com/user/red_VIII/media/photo8_zps5232234c.jpg.html]
[url=http://s1329.photobucket.com/user/red_VIII/media/photo9_zps895a042b.jpg.html]