Most aftermarket cylinder head manufacturers offer stock replacement and racing heads. Hooker headers will accommodate the stock replacement head in most cases. If the aftermarket head uses an angle plug configuration, the Hooker header for that application will have footnote 62 which says that it will fit with angle plug heads. If your aftermarket head is a straight plug stock replacement, the Hooker header for your application will fit. Most aftermarket racing heads have raised exhaust ports. Most Hooker headers are designed around the stock port height and will not accommodate the raised port heads. Hooker will produce headers for raised port heads when that particular head becomes the standard (for example: Super Competition header #6225 fits 1979-93 Mustangs with the popular TFS Twisted Wedge Race Head).