2008 LY6 swap keeping the cats help

[Ghost10]

Quick question. I plan on keeping the cats on a swap to attempt to have an old vehicle that I can park in the garage and drive without overwhelming fumes. I also would like to keep it quiet. I will run a stand alone charcoal canister on the tank but not a factory setup with purge. The engine will be left stock . I even plan to run a stock style air box. My main question is do I need to keep the rear O2 sensors to retain the cats? Do they simply monitor to set a CEL. Or do they actually trigger the ECM to modify the afr and timing if they get a bad reading. I want the best running system but do not want to over complicate it either. Plus extra sensors are just extra money. I have conflicting answers from what I consider 2 good tuners.
2008 Silverado LY6 6.0 with 6l80e setup. E38 ecm. No dod, drive by wire.
Thanks

[5FDP]

No, the rear sensors are technically not required to keep the cats. Just have to set the codes correctly for them and it's really not an issue.

The front sensors are the only ones that really matter for any fueling corrections when keeping closed loop fuel control.

[verlon]

do they actually trigger the ECM to modify the afr and timing if they get a bad reading.

They do and with rear O2s missing ECM will command slightly richer than needed for optimal cat conditions. But it is not that crucial.

[edcmat-l1]

If your concern is about garage fumes, I'd also suggest you use a modern fuel tank that's sealed up. The old vented to atmosphere tanks will smell up a garage overnight.

[Ghost10]

If your concern is about garage fumes, I'd also suggest you use a modern fuel tank that's sealed up. The old vented to atmosphere tanks will smell up a garage overnight.

As mentioned I will be running a charcoal canister ( vapor trapper ) I agree that?s part of the equation but only half. I also want to eliminate the running fuel fumes

[verlon]

I also want to eliminate the running fuel fumes

Without rear O2, a slight odor will be noticeable for the first 2 minutes after a cold start.

[Ghost10]

Without rear O2, a slight odor will be noticeable for the first 2 minutes after a cold start.

I?m guessing there is no real issue with keeping them either. So long as the cats are working correctly, no added headaches?

[Cringer]

Personally, if I am going to keep the cats, then I am going to keep the rear O2s. The ECM will be much happier.

[edcmat-l1]

Personally, I am going to keep the cats, then I am going to keep the rear O2s. The ECM will be much happier.

Agreed. Especially if they're OEM cats and not aftermarket hi flows.