Tokicos new D spec shock and strut package is our favorite for street to race Mustangs. The wide range of adjustment means you can set your Mustang up for road course, drag race and street. D-Specs are a multi-use product thatís the result of sophisticated piston and valving design and utilizes a unique variable-aperture bypass, which is controlled by an adjustable slide valve. D-Spec (damping specific) adjustments change both rebound and compression damping simultaneously. Between maximum soft and hard settings, the D-Spec is infinitely adjustable.