Well I don't have a cat but that was my first guess. After a couple of months and finding the winter stockpile I concluded it must be a rodent. I bought it from a mod here in Co Springs CO but I forget his name. Maybe has an idea.
I'm just wondering if it's still somewhere on the bike but I only smell it when the bike is running, the hotter the worse it is. Looked in the Y-pipe yesterday and looks fine