I can tell you how the steps and how long it takes to do just the cats.
Use of a roll-on lift saves at least 1/2 hour of time. This is becasue the two rearmost underbody panels need to be removed. Use of a non-roll-on means the car needs to be placed on boards to raise it enough for the lift arms to fit underneath. Also you need to crawl underneath and remove the screws that would be hidden by the lift pads before raising the car. Also be careful in where you place the lift pads.
You need to:
Remove 2 rear most underbody panels
Remove rear bumper
Remove rear valance panel
Disconnect the battery, do so before lifting
Job took us 2 1/2 hours. Should have taken 1 1/2 to 2 hours but we had a learning curve.
BTW I do not know if the Borla system is an easy replacement or requires persuasion especilaly on the plumbing. Does it use the same hangers and fittings? I am not sure if any memebr actually knows this information. Space is extremely limited especially on the passenger side of the engine. Persuasion becomes extremely difficult
Dave