(from page 1 of the 2006 Collection)
The engine is a 4.6 liter 325HP V8. It has the FR1 power pack which includes a 90mm cold air intake, performance calibration, cat-back performance exhaust, a special muffler kit, and an X-pipe similar to the one found on the GT500. A special tuned engine was also available on the 1966 version. Remember, this was only available at the Hertz rental car agency. It's hard to find a 1966 Hertz GT-H with the original engine as many were swapped out by the people who rented them. When was the last time they checked the engine when you returned a rental?
(from page 16 of the 2006 Collection)
The Ford racing upgrades to this GT, 4.6L, V8 engine adds 25hp and 10 ft-lbs of torque.