With the initial success of the Gran Sport, Buick added several variants when the 1968 redesign occurred. Now available as the California Gran Sport, Gran Sport 350, Gran Sport 400, and eventually the Gran Sport 455, Buick had a GS for everyone. The top-of-the-line GSX offered more torque and standard equipment than any other muscle car of the era. But if you want to bring your GS into the modern era, we have everything you need to bolt a Gen III/IV LS between the framerails.

Holley is home to some of the top-performance exhaust brands in the world. Brands like Flowmaster, Hooker BlackHeart, Hooker Classic, Flowtech, APR, Dinan, and Flowmonster combine to cover thousands of applications and a variety of budgets. Whether you are putting a full stainless steel exhaust on your late-model muscle car or if your rat rod needs a set of Lakester headers, Holley’s exhaust brands have you covered.