I believe MAC, BBK and Ford Racing all make headers designed for GT40P heads on a 5.0 in a Fox Mustang. Could someone post what part numbers they are? The sites I've been looking at don't seem to differentiate between stock heads and GT40P heads. Thank You.
That's what i've heard/read. so unless your looking at used ones, any new fms will work. I got new mac's off ebay for $150 shipped. I'm not a big mac fan but they fit really well, look to be good quality, i think the problem with them is the individual flanges after they've been run an heated up an taken off.