This document provides recommended installation guidance for automatic flight guidance and control systems (AFGCS) for small fixed-wing airplanes (FAR Part 23). These systems allow the aircraft to be flown smoothly and precisely according to either the flight plan or to direction from air traffic controllers, while the pilots direct the rest of their attention to other cockpit duties. A full-featured AFGCS improves safety by protecting the aircraft from incursions outside the flight envelope and maintaining predictable flight path. It may also fly approach to landing and complex departure and arrival procedures more reliably and accurately than a hand-flown aircraft. This document addresses technology and feature improvements affecting the safety and performance of the AFGCS, including the recently-published MOPS DO-325