How to Increase The Value of Modified Muscle Cars

By Charlotte Iggulden

Restomods and Number-Matching: How much should you modify a classic American muscle car?

To restore or modify is the heated and eternal debate to many muscle car enthusiasts. 

Sixties muscle cars were bought based on their performance. They were built to spec for hot rods and professionals alike; their raison d’être was work during the week and drag-strip in the weekend. It was all about speed. Each model year had its place in the evolution of the car manufacturer, either in performance, handling, or both, in the search to find that elusive power-to-weight ratio. The early Shelby Mustangs won races, the first Mach 1s set speed and endurance records. 

Some, like the drag-race ready 1970 Chevelle 454 LS6, had the highest-powered production engine ever made and a perfect power-to-weight ratio. Unfortunately, many muscle cars, especially those with larger engines, had inadequate chassis and suspension; they were plagued by poor manoeuvrability and understeer, especially at low speed, giving an uncomfortable ride. Some buyers at the time preferred performance cars with less powerful engines if they had better handling. 

To Restore Or To Modify?

Classic car restorations help to preserve a piece of history. For purists, the car was already perfect when built. ‘Survivor’ cars are kept original by collectors with OEM (Original Equipment Manufacturer) parts or as near original as possible, rebuilt to factory spec. Depending on how much it is used, poor handling might be acceptable, if the car is only taken out on the weekends or for car shows. 

However, if you want to drive your classic on a regular basis or go on a road trip without it overheating, it might make sense to make some upgrades. Restomods combine restorations and modifications, so the car can be used for modern-day traffic. They keep the classic car look but combine it with modern technology, enhancing performance, comfort, handling, and safety. However, it can be expensive, and it is common to spend more than the car is worth. 

Muscle car restorations, on the other hand, can be even more expensive, but the car is less detrimentally affected at the sale. For this reason, financing is often available for restoration projects. 

From my family’s perspective of owning classic cars, it is worth improving existing parts, so long as you maintain the car’s classic styling, unique features, interior and character. You do not want to remove its history. It should look period correct, not like a different animal. Find original pieces to enhance the vehicle’s look and increase its value, without damaging its integrity. 

If too modified, it is no longer a classic muscle car, which is identified by its distinctive looks. Performance and styling modifications are generally not beneficial to muscle car value, as customising is not to everybody’s taste. 

Not many would take kindly to someone ‘updating’ Michelangelo’s Sistine chapel. If not restored by a professional, a beloved masterpiece could be transformed into something unrecognisable, inciting anger from many. Muscle cars are collectable classics. Even unrestored barn finds can reach a significant sum of money at auction. 

Despite its dents and mismatched paint, the first-assembled and unrestored Shelby Cobra with all of its original parts sold for $13.75 million in 2016. This is referred to as a ‘number-matching’ car, when a particular car still contains its original major components or has new components that match the originals exactly. 

|| Important Note: Never restore a rare, number-matching car. It’s not worth the money, or the hubris!

Is Restoring A Classic Muscle Car Worth it?

Not all muscle cars are so rare. A base or lower-powered 1969 Ford Mustang, Plymouth Barracuda, or Chevy Chevelle will have less value than limited edition ones with performance specifications.  With the advancements made in car manufacturing, technology, brakes, and suspension since the 1960s, some argue it is worth upgrading these more common cars, so long as you have the original pieces to replace them again if necessary. 

|| TIP: If the car is not number-matching or has all the original equipment, it might be cost effective to make it look original but with modern technology. 

Many surviving Hemi ‘Cudas have even been restored to better-than-factory condition. Some restored barn finds are powerful retorts to criticisms of the cars at the time. Award-winning restomod builders, the Ring Brothers, create their muscle cars in the way they feel they should have been made, had the technology been available. It’s always tempting to embellish the muscle car’s already intimidating looks with more horsepower, acceleration, and other performance options.

For a long time, modified cars could not earn the same amount as desirable, rare, number-matching or restored cars. Now both can earn a good sum, especially if the build quality of the former has been done by a reputable car restoration shop. The best restomods have a clean look, honour their heritage, and are regularly listed for sale at six figures. 

But remember: cars are built to spec for a reason; serious electrical problems could occur with alterations, especially if not done properly. Assess what you have first to see their condition, then research the parts you need before modifying. Upgrade components that have a history of failing; better parts from later model years could be used. Make sure they fit and are built for the vehicle. Different modifications and possibilities for improvements depend on the condition of the car and its rarity. 

Speed-related modifications can impact insurance and decrease value, such as engine and mechanical changes, alongside anything that makes the car more attractive, like new paintwork or seats. It is best to do your research and inform your insurers ahead of beginning your project. 

Changes to classics, such as preventing the dreaded tin worm, or fixing driveability issues, can be essential to their survival, and equally enhance its value. A well maintained, serviced car will also help increase its price. An exception would be a rare barn find like the Bugatti found in 2019.

Still interested? Here are steps towards muscle car modifications that can ensure your classic car’s investment value.

How To Modify Your Muscle Car

Step1: Troubleshoot it by a professional. 

Step 2: Do Your Research.

Try not to be influenced into buying things you do not need. Always keep the original parts! This is how to estimate the value of a classic car. The most expensive muscle cars, like the $3.5 million Hemi ‘Cuda sold in 2014, are restored and number-matching, with period features like blue seats and chrome side pipes. 

The highest price for a non-matching numbers car was a well-preserved 1971 Hemi ‘Cuda convertible, which sold for $2.2 million in 2007. A few million less than would normally be expected!

Step 3: Have your car Dyno-tested.

This will show if you have lost any horsepower over the years.

Step 4: New engine or internal upgrades.

Unfortunately, having the original engine is rare; in these cases, a reliable and fuel-efficient, modern crate engine, with the option of more horsepower, can potentially increase the value. As with other modifications listed here, it is advised to keep the old engine, as you have the choice to reverse any changes if you sell the car. 

Although not visible, internal upgrades like higher-lift camshafts, lightweight pistons and forged connecting rods, would improve your engine’s performance. If not already fitted, sway bars may help to stiffen the engine bay. 

Step 5: Improve the exhaust.

Upgraded headers with ceramic coating, pioneered by NASA, can help regain lost horsepower.

Step 6: Upgrade the ignition.

Old fashioned, point style ignitions can create wear and tear and an inconsistent spark. Replace the point system with a more reliable electronic distributor, plus HT leads and new spark plugs that will give a bigger spark and retrieve lost horses. 

Step 7: Upgrade the braking system.

Muscle cars need good brakes. For such a powerful car, you want it to be reliable and safe, but not lose its character. As such, safety and comfort upgrades will fare better at sale than drastic cosmetic changes. Classic 1960s American muscle cars were usually fitted with drum brakes, which are not efficient for modern traffic or as good as disc brakes, which are more efficient at dissipating heat. Ceramic or metallic pads are also a modern alternative. 

Step 8: Improve the suspension.

To improve the muscle car’s ‘waterbed’ like suspension and handling, install modern, tighter, springs and shocks, whilst disguising these components. Installing sway bars may stop the body from flexing.

This Dodge Charger Super Bee has a bespoke chassis and modern suspension by Schwartz Performance:

Step 9: Install power steering.

Some later muscle cars have power steering, however others did not. Adding the system is not usually intrusive and can help heavier cars negotiate corners, making for a more pleasant driving experience. 

Step 10: Upgrade the tires for improved driveability.

The only contact between you and the road, having the right tires is of the utmost importance. Original polyglas tires were not good or safe. It is very subjective, but higher quality, period-style tires are always better than cheaper ones. To improve value, avoid fads like black or white aftermarket wheels.

Step 11: Quality paintwork and factory spec decal

Muscle cars have graphics or badges, which should be reapplied, if not already present. If the car has poor quality paintwork, this can be improved by a complete body respray or the cheaper option of mopping the bodywork. Ideally, the car should be painted in the original colour, or one available that year from the manufacturer for similar models. 

According to Barrett-Jackson auctions, one-off elements like pinstriping do not typically impact how the market values a vehicle, as they can be removed, but an ugly paint colour can decrease the car’s value.

Step 14: Install more efficient radiators.

Installing a modern cooling system will make the car more reliable, especially in busy traffic.

Step 15: Add seatbelts.

For purists, modern safety features, such as seatbelts, can devalue a classic car. However, not all buyers will be purists. Due to their essential nature, most car shows will overlook these features when judging, so long as they are subtle.

Step 16: Use stock or period-correct interiors.

A well-preserved interior will keep the car looking original. If redoing the interior, it might be an opportunity to consider sound insulation.

Step 17: Add disguised technology.

Many collectors today want the look of the classic cars, but with disguised modern technology, such as Bluetooth, speakers, and USB sockets. Add tasteful features such as period-correct radios.

This C2 Corvette has Bluetooth connectivity and LED lighting:

Step 18: Upgrade the lighting.

Make bulbs brighter and more practical with halogen or LED. Avoid aftermarket lights.

Step 19: Use a tasteful body build.

Avoid body kits that do not look original, or cheap chrome accents. Most buyers prefer the look and craftsmanship of the original car. To maintain its value, preserve its silhouette and unique features. 

Step 20: Install security systems.

If you do not want to lose your pride and joy, you need to consider security measures. Aside from visible deterrents, make sure you have good quality locks on your doors and wheels, fix an alarm and immobiliser. You can also fit a GPS tracking system. 

Increasing The Value of Modified American Muscle Cars: A Summary

Please note that these modifications are only suggestions. To avoid costly pitfalls and ensure your beloved classic car appreciates in value, research and ask reputable specialist restoration shops for advice, before making any deposits or important decisions on modifications. Keep the original parts. Where possible, use original stock equipment. As with any surgeon, the last thing you want is for someone to be learning on the job!

Muscle Car UK have thirty years of experience building handcrafted classic cars and working on hundreds of restorations. They have state-of-the-art facilities to provide a range of services for American, British, and European classic cars. Any expert on the team would be glad to advise you in your restoration process:

Ask For Help

Muscle Car restoration projects and services like classic car paint jobs are an integral part of the business, including car inspections, servicing, and tasteful restorations, such as suspension set up and overhaul, power steering and brake upgrades. 

As classic car collectors, they pride themselves on great customer service and ensuring you can enjoy driving a car that is in proper mechanical condition. Their combined knowledge and insight as technicians and artisans will ensure your distinctive American muscle car will be a modern work of art, and it will be reliable, safe, and fun to drive!

Author: Charlotte Iggulden

Muscle Car UK is the UK’s leading specialist Mustang and Muscle Car dealership. We import American muscle cars from the US, restore them here in the UK, and re-home them with our delighted customers.

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