The 2006 was rated at 325 hp while the 2007 was rated at 319 hp. I wondered why and goggled it. Here's the response:
Despite using the exact same Ford Racing Power Pack hardware, the 2006 Shelby GT-H and the 2007 Shelby GT carry different official ratings due to a recertification process.
Hardware Identity:
Both models utilize the same Ford Racing "FR1" Power Pack, which includes a 90mm cold-air intake, high-flow X-pipe, performance mufflers, and a specialized engine calibration requiring premium fuel.
Initial 2006 Rating:
When the Shelby GT-H was introduced as a limited "Rent-a-Racer" for Hertz in 2006, Ford and Shelby initially estimated and advertised its output at 325 hp.
2007 Recertification:
For the 2007 retail release of the Shelby GT (the consumer version of the GT-H), Ford underwent a formal SAE J1349 net horsepower certification for the package. This official testing resulted in a finalized rating of 319 hp and 330 lb-ft of torque.
Legacy Discrepancy:
While some later 2007 GT-H convertibles were still marketed with the "325 hp" figure in promotional materials, the standard production Shelby GT adopted the certified 319 hp rating for its entire run.
So basically, other than "bragging rights," they put out the same hp.
Possibly ?
But a six horsepower difference truly can't be felt on the street car.
More at :
https://www.saac.com/forum/index.php?topic=20999.msg162463#msg162463