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When they serve actual enhancement purposes and are done right, car mods are great. Otherwise, they can be a total waste of time and money.

Every car owner loves to use some mods to make their car look and perform better. It has also been greatly influenced by the Fast & Furious movies and car TV shows that showcase how some mods can wonderfully spark up a vehicle. Some are indeed good, like adjustments to fuel intake, air flow and some outside frame addition that can help. Some, like nitro boosts, can be tricky. But when done right, a good mod can go a long way to enhancing a car's performance to an amazing degree.

However, some mods aren't as effective as car owners think. A few are just wasteful, doing nothing to enhance performance and can look bad. Others are actually damaging to the car in the long term and should be avoided. From transforming the frame to possibly messing up the engine, these mods should be avoided as they are a huge waste of time and money, and they can really hurt the car's value.

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Why people insist on transforming their entire car for a door it was never designed for is mind-boggling. Yet, people will insist on paying big money to have giant scissor doors set on anything from a sedan to even a pickup truck. The issue is that these doors need specific switches, which can add to the cost of putting them on.

There's also how it's almost impossible to get them to look right depending on the car, especially for the larger types. That can throw off the entire frame of the car, thereby weakening it. Hence, these doors only belong on Lamborghinis rather than a vehicle not suited for it.

It's not as damaging as other mods on this list, but short ram intake simply isn't worth the price or effort. The idea is that SRI is rammed into the engine at speed due to the velocity it enters the induction system. So, by reducing the induction path, you expand the air entering the engine, which helps the horsepower.

Good in theory, except you need to have it be a serious racing machine to feel the actual benefits which even then can only be five to 15 extra horsepower. It's cheaper than the much better cold air intake, but not really worth the bother.

In terms of utterly useless mods that just make you look not too smart, fake air vents rank pretty high. They serve zero purpose, except to tell people you couldn't afford an actual racing car. Sure, they're cheap, but that's because of how lame they are and can be a hassle on the paint.

Scoops are even worse for standing out on the car, especially when they don't match the style. They're only fun if they fly off in the middle of a drive and leave a bit spot on the car. Unless one wants to invite ridicule, these stickers should be ignored.

Related: 12 Car Mods That'll Save You Money At The Pump (And 11 That Are Garbage)

"One size fits all" may be good for clothes, but not for cars. Anyone who's driven a pickup truck, a sports car, and a sedan, will tell you there are serious differences in how they operate. Which is why a good spring and bar for the suspension is a great idea. What isn't are the "universal" springs because they aren't always set to handle each specific car.

Some can cause damage to axles as the springs should be fitted for each specific car and the wrong kind of spring or suspension can do long-term damage. In fact, almost any "universal" product, from fluids to parts, should be avoided as each car needs its specific care.

In some cases, maybe a small spoiler can be a fun decoration on the car. But for the most part, that's what it is, a decoration. If a spoiler was intended to help the car's performance, it'd have been built in by the developers in the first place. A wrong size spoiler on the wrong car will only drag it down, not make it run faster.

That's without too many owners making the mistake of putting on a spoiler far too large, which looks ugly, not to mention weighing the car down. There's also the added cost of putting it on in the first place. Hence, while some may enjoy this, there are far better ways to spend money on a car.

Related: 10 Car Modifications People Think Are Cool...But Aren't

Exhaust Gas recirculation deletion is another trick modders enjoy in hopes of turning their car into a "Fast & Furious" type machine. By removing the EGR valve, a driver can prevent the redirection of gasses into the engine. This can reduce temperature and improve fuel efficiency, while adding to the engine life.

The big downside is that this is another mod openly illegal in all 50 states as it will fail an emission test, and it can cause a knock on the engine. It's also likely to leave your check engine light on for a while and the long-term effects on the engine can be damaging. Therefore, you should delete this from a list of planned car mods.

Sometimes, an urban myth takes hold and becomes an accepted fact despite how it's been proven untrue. Somehow, the idea came that by attaching a small magnet to the fuel line, it would increase performance.

The idea is that removing certain elements in the fuel will allow the car to go faster and with better mileage to boot. However, the science simply doesn't back this up as gasoline doesn't contain these supposed metal elements. These magnets do nothing to help fuel economy and are simply a waste of time and money to keep this weird myth alive.

Catalytic Converter Delete is popular among modders as it automatically increases horsepower by reducing back pressure, so the car expels more exhaust gasses. That may sound good, but there's also a reason it's illegal in a few states, thanks to how it expels more pollution.

It's also likely to result in a failure of your annual emissions test which means at best a big fine and at worst, the car impounded. Also for every car whose fuel consumption is helped by a Cat delete, another starts guzzling gas faster. The long-term consequences simply aren't worth a little horsepower boost so avoid this trick.

Related: These Car Modifications Are Illegal In The U.S.

If done correctly, maybe these can be okay. However, the risk can outweigh any benefits. Too many owners make the mistake of putting on tires and/or rims that were never intended to be on a vehicle of this size. Shifting the center of gravity and balance of a car is never a good idea as it can throw off the entire performance.

That's without the decision to add on ridiculously huge tires that a certain car model wasn't designed to handle. Oversized rims can be as bad as they can wear at the tires and cause them to fail faster. It's simply not worth the risk just to look fancier on the road.

This is another of those baffling ideas people think makes a car more impressive. If anything, quieter exhaust is better, not just for your car, but those around you. Instead, some will try to make their exhaust louder under the belief it shows how powerful the engine can be.

A trick is some states actually have laws against exhaust being too loud and putting out more emissions means everything from further stress on the engine to guzzling more gas. It's just not worth it just to make a louder sound as you drive around.

Long-time writer online on sports, celebs, entertainment, etc. Enjoy cars in movies and various TV shows (reality and fiction) and enjoying learning more about them even as I share that with others.