Actually, the V8 is meant to have 412 hp if the converter is working correctly. I reread the article, but I haven't seen any mentioning of 500hp for that engine (Shelby supercharged engines will defintely have more than 600 and even 700 hp).
Also, the article refers an Android and iOS app called the "Virtual Mustang" app, where you can configurate your own Mustang and either show it in a scenery of your choice (using the camera of your device, tablet or smartphone), or share it with your friends. You can also listen to the engine, which is the best part...