Today my car sounded like it had aftermarket exhaust (kind of anyway) and I looked in engine bay and saw a bolt missing from catalytic to downpipe.
I had a mechanic replace cat with 034 HFC, but will throw bolt/nut in myself to save trip to his shop (they are Audi/VW perf mechanics and are always busy).
Trouble is, I cannot locate info on sec for the bolt online.

Also, is it a certain hardness (Rockwell) or anything else special about it?

Oh yeah, torque spec...

Thanks. Hopefully I get a hit on this today so I can get it on way home.

Dan