Eliminating the cats without tune?

[Jmeo]

Turning off the rear cats in the tune renders the state inspection (here in Mass anyway) impassible without returning the tune to one with the cats turned on. Then you have to drive the car long enough for 5 of the 7 systems to be “ready“. Good luck having that happen before the MIL activates again, which guarantees a failed inspection. This is why I always use the bungs and not turn off the rear cats via a tune. Have been passing Mass inspections for 15 years doing this.

EDITED TO ADD: I should have mentioned that I I was using an aftermarket tune on these cars. I am suggesting that you use the bungs instead of turning the cats off in the tune.

You can pass a state inspection with a tune. The rear 02 sensors have to be left on, therefore using the bungs with the tune. The only thing of concern (unless badly tuned emission wise -rich or lean-) that you are concerned about for passing is having no check engine light -MIL-.

I was also successful not tuning the car and only using the bungs.

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[Snakecollector]

OP: assume you already have resonator deletes from Lethal? May want to give those a try first as the stock exhaust with just the resonators gone is pretty loud... Just a thought.

 

[Epiphany]

Every mod done to a car is reversible with time and/or money, I'm not arguing that. And while you can always put the cats back on, if its post engine/component failure (related components), you are very likely to have breached the expectation of any necessary repairs to be done by Ford and their dealer network.

If the intent is to "make it scream (even more)" in concert with being cautious due to potential warranty concerns, I would (as mentioned) consider a resonator delete. In my own case, I did do a Lethal resonator delete on my '20 GT500 about a year ago now. The exhaust isn't ridiculously loud but there is a definite tonal increase when running WOT, and in a good way.

Good luck, whatever you decide to do.

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