A few things. A light (very fine) scotchbrite pad will probably get that off. So will Never-dull, with some serious elbow grease.
Get the T6. When you get them, list out ALL your mods, rider weight, elevation, temps....and I can get you close on jetting.
You will get a better fitting pipe, better looking, better performance and better sounding. It's a total win-win for you, and you won't be disappointed!!!
:thumbsup: