Know Your Mods! 13 Car Mods You May Not Know Are Illegal

One of the best parts of owning a car is being able to customize and modify it. From new rims to a full paint job, a car’s only real limit is your imagination. However, you have to be careful when modifying your car. Here are 13 car mods you may not know are illegal.



1) Loud Exhaust


Whether you’re 16 with a fart-canned Civic, or 60 with a full Borla system on your Viper, exhaust modification is illegal. On one account, the excessive noise is illegal in most states. For example, in Illinois, there is a vague law saying “Aftermarket exhaust systems or any exhaust modifications must not in any way amplify or increase noise normally generated by vehicle’s original equipment.” This is written vaguely on purpose, as a method of revenue generation. If a cop pulls you over, and deems your exhaust system illegal, there’s no real way to fight it.


Another way that exhausts are illegal is when the system installed doesn’t pass emissions, such as a straight-pipe or a catless exhaust. Straight pipes are more common on imports, specifically turbocharged cars. This is due to the concepts of Back Pressure, which is very complicated. A catless exhaust, contrary to the name, doesn’t mean removing a feline from your car’s exhaust. Your car can still “purr like a kitten” with a catless system. What it actually means is to remove the catalytic converters, which restrict exhaust flow, from your system. This is against emissions regulations, and is therefore illegal…


EXCEPT for in one scenario. If your car came from factory without a catalytic converter, you can drive it without one and it is legal. An example of this exception is the Corvette, pre-1975. These cars did not come from factory with catalytic converters. The 1969 Corvette in particular came from factory with side pipes, and no catalytic converters. These could be equipped on any Corvette pre-1975, since none came with catalytic converters, legally.



2) Underglow


This is one entry that is very, very state-specific. There is a website dedicated to the laws surrounding underglow, however, their interpretations of the written law aren’t always correct. Using has been good in giving a general idea of which states are glow-friendly. However, their interpretations of the laws they quote aren’t always the best. I’ve found it where many of the states’ laws are misinterpreted on their website.


Using Illinois as an example again (because the politicians like to write riddles instead of laws there), NeonLaws says that underglow is illegal. However, there have been many court cases and amendments that contradict that, saying that (within certain restrictions) underglow is, in fact, legal. The lesson for today is: Context is important, people!


Underglow being illegal in some states is mostly due to the distracting and confusing nature of it. Being able to view a red light from the front of a vehicle could be confused for brake lights, and white/amber lights from the rear could be viewed as headlights or running lights. Running underglow on the streets, in most states, is illegal. Running it while in a parking lot, or while parked on private property, however, tends to be legal. Or at least overlooked by LEO (Law Enforcement Officers).



3) Lowriders


Street sleds have always been a part of car culture. Whether you’re a domestic loyalist, or an import enthusiast, getting low to the ground is stylish. However, in some states, lowering your car excessively is illegal. While some states allow this modification, others limit how far from stock you can lower your car. Indiana, for example, allows you to modify the height by a maximum of 3 inches from stock bumper height. Hydraulics and Air Suspension are two ways of circumnavigating these laws, allowing you to adjust the height of your car on the fly, and raise your car back within legal limits while driving.



4) Lifted cars/trucks


Just the opposite of lowering your car, making a “Bro Truck”, or lifting your Escalade, is illegal in many states. Many states have limits on lifting your vehicle, as opposed to just a few that restrict lowering it. When you raise your car, you become a risk. Not just to yourself, but to others on the road as well. This raises your Center of Gravity significantly, making your truck more prone to rollovers. This also changes the handling dynamics of your truck, with all the flex that the suspension and frame modifications bring.


Lastly, and most dangerously, your headlights are now much higher, blinding other drivers at night. The first two are dangers to yourself, and would probably just be frowned upon. With the third, you cause danger to others, causing this to elevate (pun intended) from a nuisance to a misdemeanor.



5) Light Bars (Roof-Mounted)


This goes along with the final point of the Lifted Trucks section. By installing bright lights on the roof of your car, you become a danger to others. Headlights are mounted below mirrors for a very good reason. When they’re mounted any higher, you run into issues with mirrors reflecting the light into the driver’s eyes, and causing temporary blindness. As I’m sure you know, not being able to see is a bad thing while driving.



6) Brighter HID Headlight Bulbs


Putting in new, brighter headlight bulbs is surprisingly illegal. Many lights are made much brighter than the DOT permits, and may shine into the eyes of other drivers. One law that doesn’t make much sense, though, is the law against “smart headlights”, which would automatically brighten and dim based on if there is traffic around you. BMW has made a fully functioning system for these “smart headlights”, yet the law still stands.. odd.



7) Giggle Gas (Nitrous Oxide, N2O)


Fun to play with, not to eat! That could describe a lot of things, depending on how creative you are. For NOS, though, it’s more like “Fun to play with, not for street”. While NOS has the potential for substantial power gains, the mounting and usage of a NOS system is illegal. Not just for the engine modifications and power increases, though. If (God forbid) your car ends up in a fireball, and you’re packing double tanks and a 200-shot of that giggle gas, the paramedics could get seriously injured if they had to approach the vehicle and your tanks ruptured. Transporting NOS to and from the drag strip, on the other hand, is legal. As long as it’s done safely and properly, of course


For a limited run of their Focus tuning package, Saleen offered NOS in their cars. The bottles were included, as were all the proper hookups for installation. Connecting the bottle to the piping, however, voided all warranties. Talk about skirting the law!



8) Cold Air Intake


This may come as a shock to some, but yes, most Cold Air Intake systems are illegal on your car in 14 states (and D.C.) currently. Unless your CAI has a CARB (California Air Resources Board) stamp saying it’s legal, then it isn’t. Duh. The states that require this stamp are as follows (As of December 2019): Arizona, California, Connecticut, District of Columbia, Maine, Maryland, Massachusetts, New Jersey, New Mexico, New York, Oregon, Pennsylvania, Rhode Island, Vermont, and Washington. This modification can alter your engine’s emissions output, hence needing to be approved.



9) Racing Slicks


While these tires may give you the best grip on the track, or at the 1/4 mile, these tires are not fit for road use. The idea behind racing slicks is that they eliminate the grooves in your tire, giving you the maximum amount of rubber on the road, increasing your grip. While that may be true for the track or strip, those are prepared (and meticulously kept) surfaces. You usually don’t drive on them when there is rain, snow, or debris. on the contrary, the road is chock-full of debris, and there’s always risk of precipitation.


Wouldn’t all that grip help during rain and snow? Well, no. The reason your car’s tires have grooves is to prevent hydroplaning, or skidding over the top of water. With these grooves, your tires will sink further into the water, hopefully keeping contact with the pavement. The water where your tires are trying to go will slip into these grooves, and thus, less surface area between your tires and the road.


With racing slicks, on the other hand, the whole idea of them is to eliminate those grooves. Now, when you hit water or snow, there is no groove for the water to be displaced to. It can try to escape out the sides, but that’s a lot of water to have to move. The water can’t feasibly get out of the way in time, and your tire gets lifted by Newton’s Third Law (Every force has an equal and opposite force).



10) Train/custom horns


This is another law that is generally written vaguely, for the purpose of generating revenue. The law will generally read something along the lines of: “Any road-going vehicle cannot be equipped with a horn that emits a sharp, loud, or distracting noise”. That way, any custom or aftermarket horn that you get is subject to this law, depending on the cop that pulls you over. People that swap on horns from famous movies and such, like the General Lee’s horn, could fall under this category as well.



11) Flashing Brake Lights


This law is different between cars and motorcycles. On motorcycle, having a flashing brake light is a safety feature, and is standard on some higher-end sport-bikes. However, for some reason, the same system on a car is deemed “distracting”. Why this is the case is beyond me, however, the law is the law. Having animated brakes of any kind is illegal, technically.



12) Rolling Coal


This should come as no shock to anybody. Rolling coal is many things: dumb looking, dumb sounding, dumb, power inefficient, a waste of fuel, harmful to the environment, harmful to your engine, and illegal. When you see someone rolling coal, usually their car is also lifted way above legal limits, and equipped with illegal light bars as well. These trucks, called “Bro Trucks”, are just begging to get a ticket. Please, don’t be that guy.



13) Bucket Seats


Last, but certainly not least, are bucket seats. I personally am 100% an advocate for the use of bucket seats. However, there are certain bucket seats that are not approved for use in street cars. You’ll have to check with your local law enforcement, as well as with the manufacturer of the seats, before installing one in a road-going vehicle. However, the legal ones (which are plentiful) are incredibly safe, speaking from personal experience. Installing a four or five point harness is also recommended with a bucket seat, for further safety.


This also improves user experience, especially in a drift or autocross car. Daily driving a drift car with a bucket seat in it sounds rough, but being honest, was really nice!



Final Notes


Well, there you have it, 13 car mods you may not have known were illegal. If I didn’t mention a modification you’re curious about, be sure to check with your local law enforcement, they will be able to determine the legality of your modifications. Be careful what you drive there, though. If the car you show up in isn’t the most legal, you might get written up then and there, if the cops are having a rough day. The small fines now will be much cheaper than a massive ticket and tow bill later, if you’re caught with these illegal car modifications.


As a drift enthusiast, if I've owned the car, you can bet it's been sideways! Honda S2000, Chrysler Crossfire, 1987 Porsche (only once, *never again*), and my babies, my 1995 Notch-top SR 240SX and 1991 Red-top SR 240SX. I've had a ton of fun, and I'm looking forward to sharing my experiences, tips, and recommendations with you all!

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