But at least in my jurisdiction, I can mechanically modify the car in any way I please, as long as it still has seat belts, brake lights, and bumpers of a certain height. It doesn't even still require a steering wheel; that's not specified in the law as far as I've been able to find. (Now, if I removed the muffler and made it louder than proscribed by law, I could be cited for a noise violation, but only at such a time as I womped on the gas and actually made the noise. The car itself being _capable_ of the noise is not, inherently, illegal.)

This blew my coworkers' mind once as I unplugged the passenger-side airbag while mounting a bunch of new stuff there. Apparently in some places, it requires paperwork and certifications just to unplug a connector? Weird.