It was back in 1973 that Hirotoshi Honda, the son of Honda Motor Company's founder Soichiro Honda, formed Mugen Motorsports together with Masao Kimura, a veteran racer who used Honda sports cars and worked for the Japanese auto giant's R&D department. Initially, the independent company offered special parts for motocross bikes, then later on, as Honda expanded their vehicle lineup, they then specialized in tuning its engines, starting with the 1200cc Honda Civic.

Similar to the partnership of AMG and Mercedes-Benz, Mugen and Honda collaborated to produce racing engines, particularly for single-seaters in the junior formula categories then later on in the 90s as an F1 engine supplier. Today, the company races and tunes Honda vehicles in Japan's Super GT Championship, and enjoyed success both as a team and chassis manufacturer. As a result of this, there were special Honda models over the years that have received the Mugen treatment, and here are the coolest ones.

10 Honda Civic Mugen RR

Honda's Civic Type R is already an excellent front-wheel-drive sports car in stock form, but back in 2007, Mugen took things to the next level and unlocked more performance out of the FD2 Civic by making a special-edition Mugen RR.

Limited to only 300 units for the Japanese market, Mugen put in their own camshafts, exhaust system and ECU to the Civic and boosted the K20A's engine power to 237 hp, and was 30 lbs lighter than the standard Type R.

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9 Mugen NSX-RR Concept

Four years after the first-generation NSX's production ended, Mugen still can't get enough of Honda's game-changing sports car, and created the most extreme road-going version, called the NSX-RR Concept. Based from the Super GT NSX that competed in the GT500 class, Mugen borrowed the styling cues from its race car and gave the NSX-RR an aggressive wide body kit.

In true Super GT fashion, the 3.2-liter C32B V6 engine of the NSX-RR was mounted longitudinally, which means the roof-mounted intake scoop is functional. To cap it off, the interior received a full red suede treatment with modern switches and a Type R steering wheel to complete this one-of-a-kind concept car by Mugen.

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8 Mugen S2000

For those who didn't know, Mugen is the Japanese word for "unlimited" or "infinite", that's why we see the company it with the word "power", completing the "unlimited power" that denotes what they do to Honda's cars.

Anyway, enough of the trivia. Mugen fine-tuned the already impressive 2.0-liter engine of the S2000 by removing the torque dips in its powerband, and unlocked more performance out of it. Furthermore, the car received the special Mugen MF10 17-inch alloy wheel, a sought-after aftermarket wheel for period-correct Hondas.

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7 Civic Type R Mugen FN2

The third-generation Civic Type R had two distinct models — the FD2 for the Japanese market, and the FN2 model for the European and other international markets. As expected, the JDM model was the more powerful one, and folks from Europe got the short end of the stick.

However, the Mugen FN2 solves all the shortcomings of the Euro model from its Japanese brother. It's more powerful, with 237 hp from its K20ZA inline-four engine, and is more than 200 lbs lighter than the standard FN2 Type R. One drawback it has is that it is incredibly rare, as only 20 units were made, making Mugen FN2s hard to come by in used car lots.

6 Mugen Integra Type R

The DC2 Integra Type R is highly regarded as one of the best-handling front-wheel-drive sports cars of all time. So how do you improve on what's an already good car? Mugen had an answer, and they made the car look better by introducing a special body kit for the Integra.

Its revised front bumper design works in conjunction with the hood to pull hot air out of the engine compartment, and the big wing helps in smoothing the airflow coming out of the Type R, giving it more efficient aero.

5 Mugen Accord SiR-T

The Honda Accord is not exactly a sporty sedan when compared to its smaller siblings, the Civic and the Integra, but that didn't stop Mugen from making it perform better, as the company outfitted the SiR-T model with sporty-themed parts to bring a younger image to the Accord, without sacrificing comfort.

As a result, it received a wrap-around body kit, and 17-inch Mugen MF8 aluminum wheels. In the performance department, a special 4-2-1 headers built by Mugen itself and a twinloop muffler not only made the Accord sound better, but it also helped give a smoother power delivery.

4 Mugen Fit Spec-D

Space and functionality from a small package is what the Honda Fit brought to the table when the first-generation GD chassis was revealed in the early 2000s, and it was certainly a big hit. However, people found the Fit to be lacking in the performance side, as it had a boring CVT transmission paired to the 1.5-liter i-DSi powerplant.

Mugen saw that coming, and decided to build their own Fit Spec-D model, putting the car's performance to hot hatch levels. The car received a supercharger to boost its engine's power to 145 hp, fitted to a 5-speed manual gearbox. In typical Mugen fashion, a wrap-around kit was made for the Fit, together with a revised gauge panel design.

3 Mugen Motul Civic Si

Group A racing saw Mugen make the Civic Si into a racecar, and punched way above its weight class in the Japan Touring Car Championship. In fact, the car was so good, it won all six rounds in its class in the 1987 season.

The Civic Si was the first production Honda in 20 years to have a DOHC engine, and its curb weight of only 2,000 lbs meant it had incredible grip and responsiveness, so great that it even qualified on pole once against heavier and more powerful cars like the Skyline GT-Rs and Sierra RS500s of its era.

2 Honda CR-Z Mugen GT

Toyota was racing the Prius in the GT300 class of the Super GT Championship, which led to Mugen and Honda creating a direct challenger in the form of the CR-Z GT, turning the humble hybrid hatchback into a radical race car.

In fact, the hybrid system of the CR-Z was retained, as the mid-mounted 300 hp V6 engine was assisted by an electric motor that produced 67 hp. Debuting in the 2012 season, the CR-Z GT immediately won in the Super GT, capturing the GT300 class championship in 2013.

1 Mugen NSX GT

The second-generation NSX GT made its debut in the Super GT series back in 2017, a GT500 version of the NSX supercar that was developed by Mugen.

Producing over 650 hp while weighing only 2,271 lbs, the NSX GT is powered by a 2.0-liter inline-four turbocharged engine that Honda calls the HR417E, and is mated to a Hewland 6-speed sequential semi-automatic gearbox.