I replaced the Cat converter 5 years ago in May with a Bosal from FCP.
The warranty is for 5 years. (A triumph of engineering and marketing)
Now the pipes for and aft of the Cat unit look very rusty and the rear O2 sensor
nipple that's welded in, has rusted at the weld. This could be easily welded
but there's a cross member bracket in the way that needs to come out.
4 hex bolts that thread into hidden captive nuts somewhere in the floor assembly.
Two of the bolts wont come out, and just spin.

Can those nuts be seen perhaps by pulling the passenger seat and carpet ?

Thanks, Bill