Changed mine the other week and couldn't see anyway of removing it without disconnecting the exhaust and no way of getting the Arb back in without damaging the paint and car.
I dropped the exhaust off at the end of the cat and removed the heat shield above. Even then the old one scraped so when refitting I put a cover over it and pushed it back. Did this working on my back so with a ramp and an extra few hands it would have been loads easier