RIGHT CATALYTIC CONVERTER FAILURE old news

I've had this warning light on since the time I replaced the OEM 42LRE Tranny with the Barney Purple 42LRE. The stealership at Victorville Motors swore up and down it was the Right Manifold leaking and replaced it. That was awesome since the cost of the manifold was $241 vice the Cat at +$1300 for the CA legal version. That was all well and good until the damned light came back on about 1500miles ago.

Any ideas how critical it is to knock this repair out immediately?? Bearing in mind I'm running the modified exhaust and RIPP v2 Super Charger