6 Illegal Car Modifications In Missouri (Updated For 2022)

Are you living in Missouri today? Are you planning to do a modification on your vehicle? If you live in Missouri today, or you might be planning to move to Missouri and want to modify your car and want your vehicle customized, this article is for you. 

You need to know the laws and regulations to make sure that your vehicle is legal on the street. And that’s why you need to know which vehicle modifications are considered illegal to know which modifications you can do and which modifications you must avoid. 

Modifications like tinting of dark windows, modification on your exhaust system so that you can drag race, or changing the appearance of your vehicle by putting some neon lights on the bottom, can be illegal. Each state of the United States has different laws and regulations, and these have fines that will depend on every state. 

With that, this article is made to help all of you who want to know what are illegal vehicle modifications in Missouri. This article will help you decide which modifications to proceed to. 

You must comply with these rules to not conflict with the law. So let us start.

Illegal Car Modifications In Missouri

Illegal Car Mods In Missouri

These are the illegal vehicle modifications in Missouri that you need to follow.

1. Sounds And Noise

There are laws regarding vehicle sound systems and mufflers in Missouri. Missouri does not have specific guidelines on the sound system other than the noise coming from the vehicle. The noise must not be a nuisance to the welfare or the public’s health within the city’s limits or a half-mile of the city limit.

2. Mufflers

The mufflers are required on all vehicles, and they all must work properly. The mufflers must also prevent unusual or excessive noise. Therefore, the muffler cutouts are not allowed, and any muffler openings must be attached in a way that must not be turned on or opened if the vehicle is in motion.

3. Frame And Suspension

Missouri does not have any restrictions regarding the frame height or suspension lifts. However, it does restrict the height of the bumper. In the GVWR under 4,501, the front bumper height maximum must be 24 inches, and the rear is 26 inches. 

In the GVWR 4,501-7,500, the front bumper height maximum must be 27 inches, and the rear is 29 inches. In the GVWR 7,501-9,000, the front bumper height maximum must be 28 inches, and the rear is 30 inches. In the GVWR 9,002-11,500, the front bumper height maximum is 29 inches, and the rear is 31 inches.

4. Engine

Missouri does not list the engine modification or swap regulations and illegal things, but the counties of St. Charles, St. Louis, Franklin, and Jefferson will require emissions testing.

5. Lighting And Windows

Three auxiliary lamps are allowed on the front, and they must be mounted between 12 inches and 42 inches. The White lights are required for illuminating the license plates. The Two fender or side cowl lamps are allowed to emit yellow or white light. 

One running board courtesy lamp is allowed that emits yellow or white light. One spotlight that does not glare on or dazzle another individual is also allowed.

6. Window Tinting

The Non-reflective tint is allowed if it is above the AS-1 line, given that the manufacturer provides it. The Frontside windows are allowed over 35% of light through. 

The Backside and rear windows can have any darkness, and the Front side and back side window reflective tint cannot reflect more than 35%. The Side mirrors are required if the back window is tinted.

Is All Car Modding Illegal In Missouri?

No, not all car modifications are illegal in Missouri. But unfortunately, there are several illegal modifications in Missouri. 

However, not all modifications are illegal. Therefore, you have to learn which are legal and which are illegal. 


In summary, there are people residing in Missouri and people still planning to move into Missouri. And these people are curious about the illegal modifications on every vehicle. 

There are many illegal vehicle modifications that you can do to your vehicle. It would help if you avoided these modifications.



Image credits – Canva

Share on:

My name is Hank, and I've been in the automotive industry for 27 years. I've been working in my own auto repair shop for the last 13 years, and now I want to help you here, on my blog. Let me know if you have any questions. Read more