RETROFIT

v. install new equipment or technology into older existing machines or equipment; modify something by adding newer and more advanced equipment (i.e. retrofit an old building with earthquake-safe materials)

Retrofitting refers to the addition of new technology or features to older systems. An example of this is car customizing, where older vehicles are fitted with new technologies; power windows, cruise control, remote keyless systems, electric fuel pumps, etc. Particularly popular amongst auto enthusiasts is the process of correctly retrofitting OEM HID projectors into their outdated factory or aftermarket headlamps. The whole system is purchased off of such auction websites, where through careful assembly, the head lamps are opened and worked on.
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Noun
1. a component or accessory added to something after it has been manufactured
(hypernym) component, constituent, element
2. the act of adding a component or accessory to something that did not have it when it was manufactured; "the court ordered a retrofit on all automobiles"
(hypernym) addition
Verb
1. provide with parts, devices, or equipment not available or in use at the time of the original manufacture; "They car companies retrofitted all the old models with new carburetors"
(hypernym) supply, provide, render, furnish
2. fit in or on an existing structure, such as an older house; "The mansion was retrofitted with modern plumbing"
(hypernym) install, instal, put in, set up
3. substitute new or modernized parts or equipment for older ones; "The laboratory retrofitted to meet the safety codes"
(hypernym) overhaul, modernize, modernise

n. retrofit, retrofit-catalisator

Addition of a pollution control device on an existing facility without making major changes to the generating plant. Also called backfit.