With 670 horsepower on tap, Roush’s Stage 3 Mustang will keep Hellcats honest

Roush Mustang

If you’re looking for a fast muscle car, you’re living in a golden age. One could certainly make that argument given the field of high-horsepower beasts from which we can choose.

To start with, there’s the 707-horsepower Dodge Challenger Hellcat, a car as famous for its online exploits as it is for its tire-shredding performance. Beyond that, the 650-hp Corvette Z06 sits in wait like a coiled and angry jungle beast. Then there’s the Chevrolet Camaro ZL1, Dodge Viper, Hennessey HPE700 Mustang, Saleen 302 Mustang, and about a dozen other ways for V8 enthusiasts to upset the neighborhood watch. Like we said, a golden age.

Well, a new challenger has arrived, and it’s called the Roush Stage 3 Mustang.

The American tuning company teased its RS3 kit in March, opening its order books but keeping final output numbers a secret. The brand baited the market with a figure in excess of 630 hp, so we figured the Stage 3 would net around 645 hp or so.

Roush Stage 3 Mustang

It would appear we’ve underestimated Roush slightly, as the group confirmed this week that the $21,995 kit produces a whopping 670 hp and 545 pound-feet of torque. Figure in the Mustang GT’s base price of $32,300, and you have a few shades less than 700 ponies for $54,295. For reference, the Challenger SRT Hellcat costs $59,995, but weighs about 700 pounds more.

All that extra grunt comes courtesy of a 2.3-liter TVS supercharger, which pushes out max power at the V8’s 6,800-rpm redline. The RS3 also equips a Roush quad-tip exhaust system, an adjustable coilover suspension setup, and an ‘R7’ body kit with exclusive graphics and badging.

A three-way ‘TrakPak’ coilover system is optional on the Mustang, as are 20-inch wheels, branded leather seats, and other aesthetic accents.

Take a look at Roush’s highlight video below for some detail shots of the Stage 3 car.