The phrase "to add a kit" means to include or attach a set of tools, parts, or materials to something to make it complete or functional. Full definition
All three are well equipped, while all three can also be upgraded to «Pro» spec that adds kit such as air suspension and other goodies in a bundle, rather than adding them individually. (autoexpress.co.uk)
GTS cars cost a lot more than standard 718 and 718 S, but they come with added kit that makes them even better to drive. (autoexpress.co.uk)
The Driving Assistance Pack adds kit like adaptive cruise control, lane - keeping assistance and blind - spot detection. (carbuyer.co.uk)