1979-93 Ford Mustang Foxbody, Headers with 1-7/8" diameter primaries and 3.5" OD (outside diameter) merge collectors for 9.5" tall deck aftermarket heads. Designed for use with cylinder heads that have a 3" wide horizontal in-line bolt pattern across the cylinder ports. Set up to work with TH400 auto transmission, and works with either UPR or AJE K-members / trans-crossmembers. Headers fit the following heads for the 9.5" tall deck: AFR 205/225, Dart 210/225, Ford Performance Z304, Pro Topline, World Windsor Jr/Sr. This header kit comes with high flow cats.