The best way is not to gut one. I would not gut one as the flow is so distrubed by what is left it is almost if not worse than what you had before. Ebays sells test pipes for about 20 bucks. Get one of these to use and you will still have your cat intact for inspections.
In Michigan we don't have inspection either, but if you have you car worked on by a shop, they are supposed to be required by law to report you. So keeping the catylitic there, at least for looks, will keep you safe. And that's what's best for some, I have no cat no shell, but I do ALL my own work, some can't so it's a good idea to just gut the cat.
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