An ambitious project car is not something that can be rushed, especially when you’re trying to combine modern technology with a classic chassis. In the case of Formula Drift Champion Vaughn Gittin Jr. and his RTR-X Mustang, Twin Turbo Motorsports and the Need for Speed team were tasked with essentially building a whole new car from the ground up. Fitting that new 5.0 liter V8 from Ford under the hood of a 1969 Mustang fastback is no small feat, after all.

However the engine is in, the car runs, and the RTR-X Mustang is now at the point where it is ready for some dyno tuning and testing. Speedhunters was there with a camera to catch the dyno run on video, so we can all enjoy the awesome song of this monstrous Mustang.

In case you’ve been living under a rock for the last year, we’ll recoup just what Gittin and his crew have planned for the RTR-X Mustang. Built on a reproduction 1969 Mustang body, the RTR-X is basically an all-new car in a classic body. From the all-new 5.0 liter V8 engine to the Ford to the six-speed transmission to the modern suspension system that rewards the RTR-X with an amazing turning radius, this is a purpose-built race car with those classic Mustang looks.

So how does this bad boy, which we last saw at the SEMA show in November, do on the dyno? Not too shabby. While final tuning is still in order, the RTR-X Mustang was able to put 401 horsepower and 378 ft-lbs of torque down at the wheels on 91 octane pump gas, which works out to around 460 horsepower and 434 ft-lbs of torque at the crank (though they claim more like 480 hp and 450mft-lbs of torque, given a generous 20% drivetrain loss.) This one-off project is entering the final stages and is close to being finished, so we wonder what Vaughn Gittin Jr. has planned for his next project?