Other mechanical upgrades include the KW race suspension and Stop-Tech brakes with six-piston calipers and 380-millimetre rotors up front and four-pot calipers with 355-mm rotors at the rear that came straight from the barely street-legal Dodge Viper ACR. According to the Chrysler folks, with only a few exceptions, the Dodge Challenger Targa was built using parts exclusively available through its Mopar division.