It is a known fact that stock vehicles are, most of the time, designed without any mods to be able to attract as many different types of customers as they can. This is one reason why a stock truck will not have the same off-road abilities as a custom one and a stock car will not offer the same exhaust sound as a modded one. However, once they bought the cars, the owners start adding or removing stuff in order to have the vehicles of their dreams.

Despite the fact that there are a lot upgrades possibilities that can be purchased online or from a tuning store, most of these mods are known as illegal because the law will not allow them. More exactly, the coolest and most desired tuning upgrades are considered not legal by the cops. However, there are a few of them that cannot be noticed by the police along with those that are observed instantly.

In time, tuners have learned the abilities to hide some of the mods that could be seen by the cops and also make others look like those from the factory. Those car models that also have racing variants can end up looking like them after a tuning session. Once a person started to pay money for car mods, it can be clear that he or she will not stop.

20 Never Notice: Bigger Intercoolers

via svtperformance.com

One of the most common mods made to a turbo car is a bigger intercooler. Once the owner wants to move to the next upgrade stage, this is one of the first steps because the engine needs to be cooled in an efficient way. In most cases, a larger intercooler cannot be fitted on the vehicle without a few adjustments like larger hoses, new mounts, room in the front bumper (some plastic parts need to be cut) and so on. It may look huge if seen without any cover, but when the front bumper is fitted on the car, few people may see it.

19 Never Notice: Moderated Suspensions

via autoevolution.com

There are many types of suspensions, from light (with only 2 cm lowering) to sport with higher hardness or those low-riders with Airrides.

If the owner chooses to mount a moderated suspension, not too low, no cop will likely notice any difference and would not ask of it.

A set of sick rims and a moderated suspension can change the looks of a vehicle in a radical way. Any car enthusiast that wants and also knows how to transform his stock ride into a masterpiece project would like to start with an easier type of mod, one that is affordable and sometimes even needed.

18 Never Notice: Big Turbo Or Hybrid Turbochargers

via youtube.com

To gain more power for the engine, one must upgrade a few or a lot of parts, depending on the amount of additional horses desired. In order to be able to boost up the stock power, one of the upgrades consists in a modified turbocharger. Some tuners choose to mount a hybrid turbo, while others like the idea of big turbo. Either way, the vehicle will not gain more power if the other steps of the procedure are not met. There is also need of a bigger intercooler, as mentioned above, and a special software. This type of mod will not be seen by the cops if the hood is not opened.

17 Never Notice: Nitrous

via dsportmag.com

This type of mod is clearly illegal first of all because it is not safe for the driver to be near a high pressure nitrous bottle if there is the case of an accident of any sort.

According to Zero to 60 Times, some of the cars that receive a nitrous injection kit upgrade for the track are also driven on the street.

Their drivers make use of the precious bottle in other situations, too. However, if the owner wants to invest money in this system and not get caught by cops, he or she would try to hide it somehow.

16 Never Notice: HID Headlamps

via mrkustom.com

If the car does not come with HID headlamps from the factory, they can be added later by an authorized person if the owner wants to customize his ride. Some cars have got headlamp washers mounted on the front bumper as a stock option even if it does not have xenon lighting. If the HID headlamps are mounted properly, with a magnifier, while the front bumper has got headlamp washers as a factory setting, they won’t be recognized as additional mods by the police. However, mounting HID headlamps on a vehicle is quite illegal in all US states, according to Leelofland.

15 Never Notice: Cold Air Intake

via amazon.ca

This modification, also considered illegal, is quite popular among four-cylinder import vehicles and muscle cars. The owners choose to do it to be able to gain additional power from the engines, according to Leelofland. Even if the increased amount of power can lead to more emissions and a higher fuel consumption, a cop could not spot it if the hood of the car is still down. This type of mod is one of the first power upgrade steps that need to be done in order to achieve more horsepower. Many owners start with this along with a custom exhaust to reach the Stage 2 upgrade kit.

14 Never Notice: EGR Off

via youtube.com

The EGR (Exhaust Gas Re-circulation) system was mounted on cars with the intention to reduce the amount of nitrogen oxide emissions, but it also decreases the engine efficiency with 3% along with 3%% more fuel burned for the same level of power , according to Weather Imagery. Being such a burden for the engine, it needs to be stopped.

Even if the producer placed it on the engine with a specific task that does not mean it is optimal.

Tuners all over the world discovered that it can be eliminated physically and also deactivated from the ECU software. The entire procedure is called EGR Off in tuning terms.

13 Never Notice: Diesel Particle Filter (DPF) Off

via chiptuning.com.au

The DPF or Diesel Particle Filter was created and mounted on cars to reduce the emissions and help save the planet, but unfortunately the system is kind of annoying. The regeneration of this filter is quite different from each car model to the other. At some of them it can start suddenly, while standing with the engine on in the parking lot or while driving on the street, but at others it can only start at a constant speed that can only be maintained on the highway. If not done properly, the DPF ends up being clogged and it should be removed and deactivated from the ECU software. Tuners call this procedure DPF Off.

12 Never Notice: ECU Software Modification

via wired.com

This step is usually done after there were more than one mods made to the car and it had to be set to work in parameters. There are certain companies specialized in ECU software tuning or chip tuning that can do exactly this sort of mods. According to each upgrade the owner has mounted on the car there is a modification added to the ECU to be able to work properly and not show errors on the dashboard. There are more types of software like custom ones with a lot of mods made on the parameters of different parts of the engine or normal ones for a few extra horses and a lower fuel consumption.

11 Never Notice: Bigger Wheels

via twitter.com

Bigger wheels does not mean exaggerated ones that can be seen from two blocks away. There are car models that were also produced as racing ones, like the Opel Astra GTC / OPC. Those versions have got more wheel types that can match, like a set of 19-inch wheels. In this case, if the dimension was mounted on that type of car, then the cops cannot do something about it.

Many models come with 19-inch wheels from the factory, so this will not represent an issue.

However, if that specific dimension is not mentioned in the identification card of the vehicle, there could be some problems.

10 Always Catch: Rolling Coal

via trucktrend.com

This type of illegal mod is a waste of money, but people do not care about this, according to Zero to 60 Times. The rolling coal style is all about more fuel burnt and less power, not to mention a shorter engine life and many other problems. Police would clearly notice this mod because of the large tail of smoke behind the car. A lot of money spent just to have a lot of smoke behind and receive more attention, but go a lot slower than before. Why would someone do this kind of tuning? What would be the purpose?

9 Always Catch: Donks

via ridesmag.com

According to Jalopnik, any car with ridiculously huge wheels and a flashy strange paint can be called a donk. These are the most hated type of vehicles in the world at the moment, maybe because they are not that safe as others may think and maybe because they are quite ugly. However, those huge wheels are quite illegal and the police would notice them right away, they would not need a magnifying glass to do so. Besides the fact that they are useless and awful, these wheels are definitely expensive and no one should spend that much money on something like this.

8 Always Catch: Lowriders

via reddit.com

The stunning lowriders are the opposite of those awesome lifted trucks. According to Zero to 60 Times, a lowrider is illegal to be driven on the street because of the height regulations from various states. Because they have a well known history of gang activity that is tied to them, the lowriders can get more attention from the police than any other modified car.

If the level of ground clearance of a car is considered too low, the car is declared unsafe by the police and the owner receives a ticket or remains without it.

There are clear rules that state these things.

7 Always Catch: Undercarriage Lighting

via neonlaws.com

Go back in time a little bit and try to remember those movies with tuned cars that had lights under them. They were seen in the darkness like a red, green, yellow, blue or purple shade and back then this was very cool. Nowadays, this kind of mod is kind of popular, but it is also illegal because it can interfere with the headlights and taillights of the car or cause confusion while being driven on the streets, according to Leelofland. When they see a car with undercarriage lighting, the cops are very pleased that they can offer a ticket in return.

6 Always Catch: License Plate Frames

via youtube.com

There are two ways to place a license plate on the car: one is on a license plate frame and the other is with double adhesive tape. The first one is the most used one by most owners, but some of them just want to exaggerate a little bit and buy some very nasty stuff just to show off or stand out from the crowd. The police cannot wait to catch someone with an illegal mod on his or her car to stop them in traffic and offer a beautifully written ticket. This type of mod is known to be illegal if it covers even a little bit of the license plate, according to Leelofland.

5 Always Catch: Muffler Delete

via carfromjapan.com

Some vehicle owners decide that they want more power based on the mods done on the exhaust of the car. They choose to increase the power of their engines by installing some muffler delete pipes.

This can also lead to more noise and a lot of infractions day and night.

This illegal mod is not hard to discover or observe and the rules from various states consider it a motive to receive a ticket for, according to Leelofland. Car enthusiasts will not stop modifying their cars just because it is illegal, but these things should be known from the beginning.

4 Always Catch: Window Tinting

via twitter.com

Window tinting is only accepted on the back of the car and not on the front. Some cars have tinted windshields as a factory option, but this is accepted because it was done by the producer. Each country or state had different views over this subject like location of tinting and light transmittance. In some places it is ok to tint the front of the car with a light tint to keep the police away, according to Leelofland. It is true that a car with black windows looks stunning, but if the police banned it they surely had a serious reason.

3 Always Catch: Stance

via redbull.com

According to Red Bull, the stance upgrade made on a car can be seen as an insult to those car engineers that create the vehicles, but others believe that this is a hobby, a dream and a purpose in life.

Stancing or slamming their cars is also considered a way of life for some car enthusiasts that spend a lot of money to achieve those incredible results.

However, these mods are quite illegal and can be observed quickly by the police. No one can walk by such a car and not see its wheels placed at the wrong angle. These cars should only be made for shows.

2 Always Catch: Modified Headlights Or Taillights

via teambhp.com

Once the tuning stage started to evolve and more and more upgrades started to appear, producers from all around the world thought it would be nice to introduce headlights and taillights AM replacements with LEDs or strange shapes to add “a little additional something” to the custom vehicles of the owners. According to Zero to 60 Times, there are a lot of headlight and taillight models that are illegal because of the bad quality (they start fogging or leaking) and also because they do not respect the DoT certification. A lot of chrome, fake carbon and black paint to risk being pulled over by the cops.

1 Always Catch: Loud Exhaust

via youtube.com

This case is kind of the same with the muffler delete one, both of them being illegal mods made on cars, but this one includes those cheap loud mufflers that should not be considered tuning parts. A professional exhaust can be heard from two blocks away and can be recognized immediately in comparison with a simple sport muffler switch that is all about noise and no additional power at all. The cops will definitely pull over those cars with loud exhausts, according to Zero to 60 Times. Most countries and states have regulations about the number of decibels admitted on a certain distance.

Sources: Jalopnik.com, RedBull.com, LeelofLand.com