GGB cans, especially the Mountain Can, are very loud. Maybe not to the rider, but I can't think of a word other than obnoxious to describe when someone passes by with one. Just my experience. Reminds me of the skinny NPP cans, or Jaws.
There are two versions of the GGB... Mountain can loud, trail can is really quiet... The trail can is the quietest can I've ever had!
Just want to clarify that...