I don't think there's a way to avoid trigging the malfunction indicator light once you delete the cats. The pre- and post-cat O2 sensors are there to ensure the emissions system is doing its job - which clearly it isn't, since it's on your workbench or in your attic.
There are other tricks to try to get the sensors out of the exhaust stream enough to prevent the emissions warnings, like standoffs - someone one here has to have posted up with solutions.
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