Illegal Car Mods in Texas – 9 Facts You Should Know

Are you breaking the law without knowing it? If so, you’re not alone. Many car owners make modifications to their cars without realizing they’re breaking the law.

The state of Texas has certain laws when it comes to modified vehicles. If you have just put on a new body kit or want to upgrade the engine, I’m sure you’re curious about what modifications are legal and what modifications are not.

Illegal Car Mods in Texas
Credit: Wikimedia Commons

Here are some of the most common illegal car mods in Texas, as well as relevant laws that prohibit them.

Texas headlight laws

Texas headlight laws require that you have your headlights at nighttime and when visibility is less than 1,000 feet. This includes driving through fog, snow, or other conditions that limit visibility. In fact, the law says that if your windshield wipers are on, you must have your headlights on.

Exceptions to this rule exist when the vehicle’s headlights are not functioning properly. If this is the case, you must turn on a pair of lighted lamps at least 500 feet ahead of the car and maintain them until you reach a place where you can repair your lights. Taillights must always be turned on in accordance with Texas tail light laws.

It’s not hard to spot a driver who isn’t following the rules of the road. One of the most common illegal car modification in Texas are headlights that aren’t properly equipped for nighttime driving. The exact rules on this issue vary from state to state, but nearly all states have strict rules requiring motorists to have at least one headlight that illuminates the road at night.

Some illegal car mods in Texas which violate the headlight law includes:

Are Colored headlights are illegal in Texas

One of the most common illegal car mods in Texas is using colored headlights. Blue, red, or green colored headlights are illegal in Texas. You can purchase and install LED, Xenon, and super blue halogen headlights because although they are marketed as blue, the wavelength of their light is white.

Modifying your headlights to other colors is not only illegal but dangerous as well. If you were to use blue, red, or green headlights, you’d be less visible to others and your road visibility will be impaired as well

Texas Exhaust Modification Law

Texas law definitely applies to vehicle modifications. Since this is the case, you must familiarize yourself with top illegal car mods in Texas that apply to exhaust system modifications. One area of concern is whether or not you can modify your muffler and tailpipe.

Texas does not have an official law about exhaust system modifications. However, there are regulations about the muffler itself, and these could be used against you if you make modifications. For example, Sec. 547.604 of the Texas Transportation Code states that your muffler must be completely intact and must not contain any perforations.

Exhaust Noise and Emission Laws

Texas has no defined noise limits for your car or truck’s exhaust system. So it is unclear if it is one of the illegal car mods in Texas. While this may give you the impression that you can modify your exhaust system as much as you want, that’s not entirely true. If a police officer decides that your exhaust is too loud, then you could get a ticket for violating local noise ordinances or disturbing the peace. This is why it’s important to have a muffler and not a straight pipe when modifying your vehicle’s exhaust system.

Related: Black Smoke From Exhaust: Top 4 Causes

In Texas, you are required to pass an emissions test when you renew your vehicle’s registration. If you receive a passing score, then you’re free to modify your exhaust system as long as it doesn’t produce more emissions than the legal limit. If you want to install new modifications or add anything to your exhaust system, then you must present a letter from a certified emissions testing facility that states that your modifications do not increase the overall emissions of your vehicle.

Are Exhaust System Modifications Allowed in Texas?

Another illegal car mods in Texas is the addition of an after-market, or performance, exhaust system. Modifying your vehicle’s exhaust system is often done to improve engine performance, increase horsepower, and improve fuel economy. Some of these modifications can also improve your vehicle’s safety (such as a quieter muffler).

How loud can your car be in Texas? Excessive or unusual noise from a motor vehicle’s exhaust system that can be heard by a person of normal hearing at a distance of 50 feet or more from the vehicle is prohibited.

Nitrous Oxide Laws

Nitrous oxide is a legally abusable volatile chemical that can be used legally in Texas (with a prescription). If you have been charged with possession of nitrous and/or nitrous oxide for illegal use, it may help to know that there are three types of illegal use of these chemicals: recreational use, selling or distribution, and manufacturing/homemade use.

Nitrous oxide, more commonly known as “laughing gas” or “noz,” is a popular street racing drug because it allows racers to squeeze more horsepower out of their cars for short durations of time. And if you’re going to street race, it’s pretty much a prerequisite that your car has at least 100 extra horsepower than the next guy’s ride. Nitrous is also popular with drag racers, who use it to get off the line quicker and win races by mere milliseconds.

Is Nitrous Oxide illegal in Texas?

No. Installing NOz is not considered illegal car mods in Texas. However, it is not legal to use the substance for street racing purposes. To avoid breaking the law, you should restrict its use to sanctioned drag races or other speed competitions approved by local authorities.

Texas Window Tint Darkness Laws

The Texas Department of Public Safety (DPS) has a list of rules and regulations pertaining to window tinting. Window tint darkness is determined by the percentage of light allowed through a car’s window film and glass. Cars with dark-tinted windows have been involved in several high-profile crimes, including some murders and sexual assaults. Texas law states that the windshield may have a minimum of 25% VLT. Front side windows are required to allow more than 25% of light in. Backside windows can be any darkness.

If you are pulled over in Texas for having dark window tinting and do not have a medical exemption, you face potential fines and penalties. Keep in mind that even though many police officers will let you off with a warning the first time they stop you for window tinting violations, this is still technically a moving violation and will count toward points on your driving record. You may also receive demerit points on your driver’s license.

Are window tints allowed in Texas?

The amount of light allowed through your car’s windows is measured as a percentage. This percentage is known as Visible Light Transmission or VLT.

Tint darkness limitations on sedans:

  • Windshield: 25% VLT tint is allowed above the manufacturer’s AS-1 line or top 5 inches, with less than 25% reflection
  • Front Side windows: Must allow more than 25% of light in.*
  • Back Side windows: Any darkness can be used.*
  • Sedans must maintain outside mirrors to 100% reflectivity. The DPS does not specify the tint percentages for sedans, but does require that the vehicle is not “obscured.”*

Tint darkness limitations on SUVs:

  • Windshield: No restrictions are placed on windshield tinting.*
  • Front Side windows: Must allow more than 25% of light in.*
  • Back Side windows: Any darkness can be used.*

If your car’s tint is too dark and doesn’t follow the abovementioned requirements, then it’s considered as one of the illegal car mods in Texas.


Texas has very strict laws when it comes to modified vehicles, in part due to the high number of street racers in the state. A well-planned modification will not cause a problem in the eyes of the law, but be aware of the laws—and be prepared for any potential problems that may arise as a result.

The bottom line is that you need to make sure that any modifications you make to your car are legal in your state before you put them on. It’s also important to remember that not all laws are written down, so even if a modification isn’t specifically mentioned in any written law, it might still be against a law. In these cases, it’s best to err on the side of caution and get proper legal advice before making the modification.

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