Why would you assume it's a pushrod engine? The Mustang hasn't had a pushrod engine since 1995.
The engine is a 4.6L DOHC mill with a supercharger.
But your statement still doesn't make sense, because whether it's DOHC, SOHC, pushrod or even side valve, it's still >600RWHP, which, regardless of the valvetrain configuration, your use of the phrasing "it's no rocket ship" seems completely off the wall coming from a guy with the vehicles you have listed in your signature. That's what raised my eyebrow. My DD is 475HP, and I'd consider a 600+RWHP Termi pretty darn fast for a street car.