In the mid 1970s, Beech added the 58P Pressurized Baron to its twin range. Its cabin system is pressurised to 3.6 psi for sea level at 7,800 . The 58P also has rear double doors on the port side rather than starboard. Initial models had 310 hp TSIO-520 engines but these were uprated to 325 hp in 1978. Nearly 500 58Ps were built from 1976 to 1988.