If its a service you dont have to pay for Galpin has been great for me. They are really expensive if its not warranty though. It was almost 700 for an oil change.
The videos where they sound really cool have their headers and no cats. I know at least on their first go they had a bad header design and the o2 sensor wasn't in the proper location. I'm not sure if they ever fixed that.
Doubtful you would have both just knocked off without noticing. They are pretty loud in the cabin when they scrape. They would make a heck of a racket getting knocked off. You probably just never had them installed at the factory.
The problem with the GGLC site is that its really only the Norcal guys keeping it updated. I hear the Socal crew is using instagram to organize but havent really confirmed yet.