Ever since the unveiling of the 2015 Mustang, Hennessey fans have been waiting anxiously for the moment when they could order a performance kit from the legendary tuner. And now that they're out, those fans had better act quick, because Hennessey is building just 500 each of the HPE600 and the HPE700, the only kits released for 2015 thus far. The HPE600 will raise horsepower to 620 and torque to 595lb-ft.

This is accomplished with a 2.3-liter supercharger and costs $14,950. The second kit is the HPE700, which boasts 717 horsepower and 632lb-ft of torque from a 2.9-liter supercharger, for a price of $17,950. There are no performance figures for the HPE600, but the HPE700 is said to produce a 0-60 time of 3.2 seconds and an 11.2-second quarter mile. Also offered is the Carbon Aero kit, a $7,450 option which gives you a new front splitter, side sills and a rear lip spoiler. Lastly, there are your choice of 19- or 20-inch wheels for $6,950. All told, it's only about as expensive as the new Shelby GT500 is likely to cost, but makes for a much more special and exclusive vehicle.