If you are wanting to do a LARGE decal, you might want to get vector art originals. Most of the stuff posted on here is low-resolution and will not look good enlarged. I have a lot of stuff in vector format, so if you can let us know specifically what you're wanting to print maybe I can provide the file for you to send to Jen or Moto (or whoever you want to use).
We can make just about anything into a decal, sign, or flag-banner We can use Shanman's stuff it is great and looks good all they way up to say 5foot tall.
I kind of like the Fort Fiends, Long Live Musket Mickey that Shan-man has, I will get the measurements for you. 22" x 48" would cover the King of the Road emblem nicely..