The Shelby Mustangs proved to be fast, brutal and successful in competition. Like the exotic Shelby Cobras these extremely powerful cars were street legal and were sold commercially. Though the Shelby Mustangs remained rare these cars had started off the "Muscle Car" era: awe-inspiring compact cars fitted with huge engines which accelerated like rockets and were the dream of every American teenage boy. Unfortunately the Shelby Mustang became a victim of it's own success: the enormous amount of accidents with GT cars, the subsequently high insurance rates and the cheaper less refined competition meant the end for the Shelby Mustang in 1970. These days the Shelby Mustang is a true blooded classic with a devoted and enthusiastic following. Driving these cars still offers a huge thrill, uncluttered by modern gadgets like traction control and automatic brake assist. The impressive roar of the engine and the demanding, involving drive sets it apart from everyday driving and adds a bit of fear to the excitement: this is no well-groomed means of transport but a pony with a bite and it needs an experienced master. I like that kind of character in a car, and that's why I hope you'll enjoy this tour around six years of Shelby Mustangs. 
For 1967 the Mustang bodystyle was altered and Shelby added a new model to his line-up; the GT500. It featured a 428 cid engine, pumping out well over 350 bhp. Where the early Shelby Mustangs were very competition oriented, the 1967 and 1968 cars were more of a combination between performance and luxury. At the end of 1968 a more powerful GT500 KR (King of the Road) was launched, which featured the 428 Cobra Jet engine. Production of the Shelby Mustangs ceased at the end of 1969, when Ford's own high performance had mostly taken over.
The first Shelby Mustang GT-350 appeared on January 27, 1965. It was based on the Ford Mustang fastback and was painted white with blue stripes, which was to remain the original color scheme for the 1965 and 1966 models. From the outside the GT-350 didn't look very different from a regular Mustang, but underneath the body many changes were made.
The GT-350 was fitted with Ford's 289 cid (4,738 cc) small-block V8 engine in "Hi-Performance" trim. This unit produced 271 hp as standard, but modified by Shelby it cranked out 306 hp @ 6000 rpm. It rendered the GT-350 a top speed of about 240 kph, quite good for a 1155 kg car.
The full racing version of the Shelby Mustang was the GT-350R, which had a 350 hp (some even 400 hp) engine, racing suspension and a fiberglass airdam with a large central hole for extra air in front which replaced the bumper. The GT-350R won the SCCA production car championship in 1965, 1966 and 1967, giving the Mustang the so desired competition car heritage.
The engine was fitted with a high-rise manifold, a bigger four-barrel carburetor and a free-flow exhaust. A fiberglass hood featuring a functional air-scoop covered the engine which made it stand apart from regular less powerful Mustangs.