10 Mods That Are Illegal (And 10 Worth Every Penny)

A car isn't really yours until you put your touch on it. Whether it's just a Lovely Layla Hula Girl on the dash or go fast bolt-on bits under the hood, adding a personal touch to the car separates it from all the other factory duplicates holding down balloons at the car lot.

But not all mods are created equal. Aesthetic modifications are one thing, while performance mods are another. A car comes from the factory balancing an equation. Affordability, power, longevity, mileage, and comfort all have to be balanced so that the vehicle appeals to as broad a market as possible.

Your blood type has an octane rating. Comfort isn't your main concern. You want to put a finger on the scale of power and cool. But be careful, you might end up on the wrong side of the law with some modification. Here are ten mods that are illegal and ten worth the money.

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20 ILLEGAL: Cold Air Intakes

via carthrottle.com

Engine performance comes down to three things: air, fuel, and spark. Get that ratio right and you've got the formula for go fast. Cold air intakes are supposed to handle the air part of that equation.

The idea is simple enough. Cold air is denser, therefore if the air coming into the engine is colder, more air gets into the engine and more power is created. But this causes 2 problems.

First, the intake system is part of the emissions system in your car. More air goes in, more air goes out. The car is meant to manage the air it was built to consume. In states like California, the intake system is part of the emission controls and is part of the inspection every two years. Unless your mod has a CARB exempt stamp, you're going to fail.

Second, it doesn't really work that well anyway. The air coming into the car from just outside the engine is not significantly cooler to make enough of a difference. In order to get air cool enough you'd need something like a snorkel more common on off-road trucks.

19 ILLEGAL: Flamethrower Exhaust

via 6speedonline.com

You have to admit, this is pretty cool. Watching a fuel-rich engine come off song and explode unexpended fuel out of the pipes is part of the theater of watching hot cars. But going with a rich mixture and a hot engine isn't going to guarantee a nice long burn outside of a wild Group B or a Can-Am race car.

If you want reliable producible flames, you have to take matters into your own hands. This is usually done by injecting a flammable element and spark to the exhaust.

Now, here's where it gets a little tricky. There is no specific law outlawing flamethrowers, but you might need to be a pretty good amateur lawyer to convince a judge out of a ticket for using one on the road. Companies that sell flamethrower kits are careful to state that it's not specifically illegal but always do your due diligence beforehand. If nothing else. they can be considered as an alteration to the emissions equipment much like the cold air intake. Still cool though.

18 ILLEGAL: Lowering the Car

via carponents.com

Lowering your car has different purposes for different people. For lowriders and 'stanced' cars, it's aesthetic. For performance enthusiasts, it's to lower the car's center of gravity. Either way, it might run you into a ticket.

How low is too low? It's a bit of a moving target thanks to the ingenuity of car modifier. In 1957 the rule in California was that no part of the body and frame can be lower than the lowest part of the of the rim. Low profile tires can help get you around that, though.

So another rule in the California vehicle code maintains that the headlights have to be no less than 22 inches off the ground, which just so happens to be a common length for a police baton. The lowrider community responded to these laws the coolest way possible. They installed hydraulics that would raise and lower the car at the driver's discretion.

17 ILLEGAL: Nitrous

via superstreetonline.com

It's a staple of the modern street racer movie. Our hero is neck and neck in a street race, stakes are high. They've already shifted through all their gears, he needs an edge. He reaches down and opens a valve on a small tank. The needle on the attached gauge rises, and once it reaches the top he hits a button and the car shoots forward spitting out blue flames. The nitrous injector saves the day.

Of course, if you're racing another kid on the street the illegal ship has sailed. Different states have different laws on the matter.

Most regulate the sale of nitrous oxide 'with the intent to breathe', which leaves out liquid nitrous. Maryland has specific laws forbidding NO2 as a 'power-adder' unless you're on the way to the track.

Not to mention that if you hit the bottle every time you need speed it can get expensive.

16 ILLEGAL: Radar/Laser Jammer

via stealthviel.com

The war between police and speeders has always been one of escalation. If the police wanted to know how fast you were going they'd have to pace you in their own car. But it's hard to sneak up on speeders if you're matching speed behind them.

Radar and laser guns can be operated from a hidden position and give the officer a fairly accurate reading of a targeted car's speed. Unless, of course, you were to jam that signal.

It's hard to argue there's another purpose for having a jammer other than to go fast without getting caught. Using a jammer is actually a federal offense, and states are quickly outlawing laser jammers.

15 ILLEGAL: Straight Pipes

via corvetteforum.com

As important as it is to get air and fuel into the engine, getting that spent fuel and air out of the engine is just as important. You have to make room for the new mixture after all. Mufflers can impede that progress as they attempt to tamp down the sound of thousands of little explosions a minute pushing the car forward.

So the obvious solution is to get rid of that muffler.

As you can imagine this has a few problems. Once again emissions is an issue plus the issue of noise. If you've ever been to a drag race you're familiar with the roaring howl of an unmuffled engine. In California, the volume of an engine's exhaust cannot exceed 95 decibels. Straight pipes would beat that with room to spare.

14 ILLEGAL: Automated License Plate Cover

via rugift.com

You're on your way to the martini bar but you have no time to lose. She won't wait forever. You're passing through the road that's marked with speed camera warning signs.

Getting a speeding ticket through the mail won't do. It's alright, you have just the technology to deal with this situation. With a flip of a switch, a cover slides over your license plate. 

While it seems pretty clever it's also a rather obviously an illegal modification. Not just the automatic cover but in most states covering any part of your plate is illegal, including license plate rims that obscure any part of your license plate.

13 ILLEGAL: Emission Delete

via reviewdieselparts.com

In the sixties, before emissions laws, full-throated engines were free of restrictions. They could use all the air they could swallow and expel all the waste emission they wanted, but environmental concerns changed the landscape. Catalytic converters meant to reduce pollutants and restrictions on input and output meant that cars were cleaner but they were far less powerful.

So it stands to reason that the best way to gain power is to take the smog equipment off the car. Of course, that's never going to be legal and it might be a hassle to remove and replace the smog equipment every two years just to pass inspection.

This particular law is the blanket that covers most of the illegal modifications.

12 ILLEGAL: Raised Suspension

via trucktrend.com

Just as there is such a thing as too low, there is such a thing as too high. Off-roaders need clearance, the more clearance the greater the obstacle they can conquer. But that comes with a price. The raised trucks have a raised center of gravity.

Raised trucks face a greater risk of rolling over. To prevent that, different states have different approaches.

The headlight law for lowriders has a minimum in most states. In California, the frame height is dictated by the gross vehicle weight as well as laws that specify the different body requirements. California's laws are the most specific of all the states, if you want to raise your truck you'll have to look it up individually.

11 ILLEGAL: Slicks/Studded Tires

via readytorace.com

The amount a car that sticks to the ground can be in direct relation to how much contact it's making with the ground. For race cars, they max out contact by putting as much rubber down as possible. Therefore, big tires with a smooth surface to provide as much grip are the norm.

Which works great in ideal conditions.

But roads are not ideal conditions. When it rains you can't come into the pits and have your crew switch you over to wets. Or predict puddles. Or debris. Or any of the other road hazards that grooves protect you from on the road.

Likewise, studded tires provide an extra amount of grip with the conditions get bad. Like a rolling cleat, the studs in the tire dig in and find the grip you'd otherwise not have. But in fair weather conditions, while the studded tires look cool, they also tear up public roads. In most states having a studded tire on in conditions not calling for it is illegal.

10 WORTH IT: Forced Induction/Intake (Super/turbochargers)

via carid.com

Back to the formula of air, fuel, and spark. The more you can push of air and fuel in, the more that spark can burn and the more power a car can produce. For most cars, you can get more power out of an engine by adding forced induction.

A turbocharger runs off the exhaust of an engine, spinning a turbine that is used to compress air into the cylinders allowing the cylinders to burn more, a sort of feedback loop of power. This also causes what's known as turbo lag, you need to produce exhaust to spin the turbo and while that's happening the engine is running without the benefit of the forced induction.

Superchargers get around this problem by running their compressors off the main crankshaft, meaning the compressor comes on faster.

Companies are now offering turbo and supercharger kits that meet with all 50 state's emission standards, but if you're in a state like California make sure to check before buying.

9 WORTH IT: High Temp Brake Pads/Fluid

via autoevolution.com

Due to emission concerns, adding power is a tricky subject. Although, power isn't the only way to make cars go faster. As any racer will tell you, races are won thanks to the brakes. The biggest enemy brakes have is heat. The more you use your brakes the hotter they get, the hotter they get the less effective they become. This is what's known as 'brake fade.'

All the speed the in the world can become a liability if you suddenly can't bring your car to a stop.

High-temperature brake pads and fluid can help with that. Pads that are designed to work at higher temperatures will help reduce fade and fluid that retains viscosity at higher heats will keep brake pressure high even under heavy use. For once, it's a modification that actually makes your car safer.

8 WORTH IT: Anti-Sway/Roll Bar

via wikipedia.com

When a car goes through a turn a lot of physics start to happen. Without getting into the math of it, inertia works its magic on the car. The tires are directing the car one way, the inertial force is pushing towards the other. The car sinks into its suspension leaning to one corner or another.

The problem with this being that it can take the weight off one or more of the tires and transfer it to another, causing a loss in traction.

This roll or sway can be mitigated by an anti-sway bar. By transferring energy from the outside tires of the car to the inside of the car, the anti-sway bar keeps the car flatter through the turn increasing grip. The side effect will be a slightly stiffer ride, but it will also be more stable while carving the canyons.

7 WORTH IT: Short Shift Kit

via pelicanparts.com

If you're lucky enough to have a car with a manual transmission, a short shift kit might be a good, emission friendly way to shorten your 0-60 times. While manuals have, at least in the past, had a lot of advantages in acceleration, their weak spot is how long it takes you to move the lever from one gear to the next. In a race that lasts only 10 seconds, every fraction of a second counts.

For most models out there, there are kits that will shorten the throw from one gear to the next. Even if you save .2 of a second from each exchange, by the time you get to the top gear you've shaved more than half a second off your time.

6 Worth It: Quick Ratio Steering Rack

via swclassics.com

If you've watched in-car cameras from a race car you might have noticed that their hands never leave the wheel. Unlike the enormous, by comparison, steering wheel in your car where to make anything more dramatic than a lane change or slide onto an offramp you need to go hand over hand, race cars can make sharp turns without changing their grip.

This is the result of a quick ratio steering rack. More than just keeping the driver's hands on the wheel, it also creates steering that is more direct and responsive. Streetcars tend to give you a little room to move to allow for smoother driving, a quick ratio steering rack can make for some twitchy driving.

But in skilled hands, it can also mean a car that is responsive to your touch.

5 WORTH IT: Good Tires

via gazettereview.com

While you can't attach slicks to your road car, you can invest in good rubber and it might be the best thing you can do for your car. All the power, all the stopping ability, all the weight transferring, all of that means nothing if the tires can't grab the road.

Everything your car does goes through the tires. The contact patch, the compound, the tread pattern, it will have more effect on how your car performs than anything else you manage to do to your car. Even more, if you do work on other aspects of your car without paying attention to the tires all of your hard earned work and money have disappeared in vain.

4 WORTH IT: Suspension Upgrade

via qu.1.net

Here's where it gets a little tricky. Your car is meant to be driven every day on roads that are less than stellar. Even in sports models, most of the time comfort is given priority over handling.

Changing your suspension set up can improve the handling. Although, it's not as simple as just making your car stiffer, as attractive as that siren is. It' easy to look at race cars and their stiff suspension and think, well if it's good enough for a race car, it's good enough for my car. Race cars have something that your Civic R doesn't, which is a whole lot of downforce. The stiff springs on the race car are working against the pressure pushing those cars to the ground.

If you install too stiff of a setup on your road car, you might actually be making your handling worse. If your suspension can't move with the terrain then you're not making contact with the ground. If you're not making contact with the ground, then you're not getting the grip you need to go fast, stop, or turn. If you go that route, you're going to have to break out the slide rule. Although, if you dial it correctly, you'll greatly improve the performance of the whole car.

3 WORTH IT: Braided Brake Lines

via ridersdiscount.com

So you went and got some high-temperature brake pads and brake fluid to prevent brake fade. If you're going to be pushing your car, you're going to be pushing your brakes pretty hard. That means that there's going to be a lot of pressure going through your brake lines to bring your hot rod to a stop.

Standard brake lines aren't meant to withstand that kind of pressure. Brake lines can blister or expand, lessening the brake pressure and stopping power. To prevent that loss you can install braided brake lines. Braided brake lines are pretty much what they sound like. They are brake lines that have steel braids around them to prevent expansion under heat and pressure.

While not the sexiest of modifications, it can ensure that you can bring your hot rod to a stop in time.

2 WORTH IT: Dyno Tuned ECU

via vividracing.com

Volkswagen showed the world what an ECU can do. When the TDI engine detected the front drive wheels turning without the rear wheels it would alter the injection map and cause the car to run cleaner than normal to pass the smog test. Then when the front and rear wheels were turning it would revert to normal injection which was more powerful but also dirtier.

The ECU or Electronic Control Unit is the brain of the car. There are a wealth of aftermarket chips available out there, but most of them aren't worth the price of postage. Just like you can't put just any chip in your computer and make it work better, every car is different and has different parameters.

Although, that doesn't mean that there's nothing you can do. A dyno-tuned ECU allows you to specifically set the priorities of your car. Keep in mind you are rebalancing an equation. If you want speed, you'll have to sacrifice something else, usually mileage.

1 WORTH IT: Lighter Wheels


There are two kinds of weight on a car, sprung and unsprung. Sprung weight is everything above the suspension that's managed by all of the bits that we've already covered. Unsprung weight is everything below, the brakes, tires, and wheels. The greater the sprung weight over the unsprung weight the more responsive the suspension is to changes in the road increasing that all important contact.

Obviously adding sprung weight has its own issues. But you can reduce the unsprung weight to improve that ratio. More important than the diameter, the weight of the wheels can have a dramatic effect on the grip of your car. Just make sure you don't sacrifice too much strength, tires don't have the suspension system to protect itself from the rough patches of road.

Sources: roadandtrack.com machinedesign.com silondrome.com findlaw.com

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