Before choosing an aftermarket head, begin by finding a set of hedders that is designed to fit the chassis with the heads you plan on using. Most aftermarket heads have different exhaust port locations, different plug angles and some even have different bolt patterns.For this reason,and to ensure that you choose the best performing hedder for your specific application, it is highly recommended that you consult with the Husler Technical department before committing to a specific hedder number. Some applications will require special shorter “peanut” spark plugs for maximum hedder clearance. Also, some applications may require special sockets or wrenches for spark plug installation.