The use of Hand-held fire extinguishers containing Halon in Aircraft will become prohibited end of 2025 and you will need to replace all them.

Replace the existing nickel-cadmium battery with Teledyne Gill G-6381E series lead-acid battery.

Installation of a heated windshield panel

Installation of emergency medical stretcher, oxygen, and electrical systems.

Installation of MASS Systems Fire Extinguisher Cartridge asreplacement for Walter Kidde Aerospace fire extinguisher cartridges in fire extinguisher bottles installed in the airplane models noted on the EASA approved model list dtd 02 April 2008 (which excludes aircraft models not validated by EASA)... EASA.IM.A.S.01853 FAA STC ST00961LA

Installation of an air ambulance conversion kit.

Installation of JPI digital tachometer.

Installation of fuel flow/pressure instruments. (W/TSIO-360-MB1)

Installation of Parmetheus Plus LED PAR36 and PAR46 taxi and landing lights.