The scope of this document is limited specifically to the following types of passenger vehicles: automobiles, light trucks, and sport/utility vehicles. This document addresses modifications as they apply to legal use of the vehicle, and examines suspension modification as it applies to stock (as manufactured) ride height, and changed (raised or lowered) ride height. Note that modifications of ride height are considered, exclusive of wheel and/or tire modifications, which can also have potentially serious side effects, and are outside the scope of this document. The scope of this document is not intended to endorse or discourage modification of original equipment chassis or settings. This paper provides guidelines describing some of the issues that must be considered when undertaking any form of vehicle suspension modification. While every effort has been made to address most types of suspension modification, this document is qualitative and is not all-inclusive. This document is not intended to endorse, regulate, or limit the degree of modification, or to be interpreted by regulatory or enforcement groups as establishing such limits.