The GT-40(P) cylinder head is popular for classes that must run a stock Ford production head. Like other stock castings, there is plenty of room for improvement with this head.
Stock air flow on this head tops out at 190 cfm intake and 128 cfm exhaust. When “Undercover Ported“, the GT-40 head will flow 202 to 210 cfm intake and 145 on the exhaust side.
“UnderCover Porting” to GT-40 heads
$995.00 labor only to 1 pair of heads
See also: Complete Cylinder Head Assemblies