In California, it is illegal to select a catalytic converter for installation based solely on vehicle weight and engine size. The design of these systems often sees an increase in horsepower compared to the factory design of a vehicle. Because stock models try to minimise materials and maximise space, with horsepower as a lower priority.

We use the latest, advanced equipment to ensure precise and accurate adjustments. Each of the trucks will be included in Shelby’s official registry. Revology’s ‘68 Shelby GT500KR surpasses the performance of the original with a 710hp supercharged Ford/Roush Performance 5.0L Ti-VCT Coyote DOHC V8 engine. In 1962 Carroll Shelby, one of America’s greatest race car drivers began a new chapter in his storied career with the legendary Cobra sports car. A piece of of this sports car’s “DNA” is part of every subsequent Shelby vehicle.

By running pipes from the catalytic converter to the muffler and from the muffler to the exhaust tip, cat back exhaust systems improve exhaust gas flow, providing small performance boosts. However, your performance gains may be limited if your catalytic converter restricts gas flow, as a catback exhaust system is installed ‘downstream’ of the converter. Header-back systems are increasingly rare, namely because of modern emissions systems. Since removing your vehicle’s factory emissions components is highly illegal, the previous two options are more common. However, header-back systems are still available for some older, pre-emissions applications. In these cases, header-back systems offer more performance and volume than cat-back or axle-back systems