...um, my car (without the emissions controls) was driven daily. Half of the mods that are done for "off public road use" find their way on to the street. With a gutted cat and MIL eliminator, any cop who pulls you over is not going to know what you've done. The casing is still there, and it looks like a catalytic converter. I would only worry about it if I lived in a state that requires annual emissions checks (like California). It would take an actual sniffer to know that the cats are hollowed out. Or, someone who understands automotive electronics well enough to know that the O2 harness has been spliced into.

Disabling emissions controls can be argued on a moral basis as well, but I expect few people on this forum to take the other side of the argument. After all, a car that gets 17 city / 25 highway is inherently environmentally unfriendly. Even if all the emissions are just CO2, that's a greenhouse gas as well!

Hollow out your cats. Go fast. And, know that you are polluting less than the hippie in the VW bus with the Earth Day bumper sticker on the rear of it.