25. Shelby GT 500
The Mustang had some performance versions like the GT with the 289 HiPo V8 engine or the Shelby GT 350 in 1965. But the first true performance Mustang with a big block engine and respectable 0 to 60 mph times was the 1967 Shelby GT 500. Bigger and more powerful than before, the 1967 GT 500 featured a new design. Also, it came with a modified front and rear end as well as a big 427 V8 engine with 335 HP and 420 lb-ft of torque.
In those days, Ford was notorious for underrating the power output of their engines and 335 HP sounded too bland for the big 427. Most Mustang enthusiasts claim that the real power was closer to the 400 HP range and the performance figures back that claim. The 0 to 60 mph time was 6.5 seconds, which was good for the day. Also, thanks to the suspension modifications, the GT 500 could handle the curves well, too.