[75 911s]

Colorado has a "Collectors Item" clause as follows:

Vehicles at least 32 years old are eligible for "collector's item" registration. However, in order to register as a "collector's item," these vehicles will require an initial emissions inspection and then must be inspected every five years thereafter at the time of registration renewal. These vehicle have a mileage restriction limiting driving to no more than 4,500 miles per year. If the vehicle is being registered in a county that does not require an emissions inspection, only the mileage restriction applies.

Looks like they also have this:

Kit cars, all-electric vehicles, motorcycles, horseless carriage and vehicles registered as street rods are exempt from emissions testing requirements.

Could you register as a street rod?

What is not stock about the engine and exhaust?