In each sector you will find a person who will take care of the condition of your equipment and (in Zaton and Jupiter) will help you improve and modify it. However first you have to bring them proper tools.

Complete makes a lot of the game easier - AI is a bit blind and you can dash at crazy speed across the map with a full load of gear. It's still a very pretty and atmospheric mod (though not as dark in tone as vanilla) and a great introduction for newer players, because it lets you focus on the plot and pacing.

The first technician you'll meet is Cardan (point 4 on Zaton map). Apart from tools, you will have to give him two bottles of vodka each time you want him to do some more complicated improvements. Thanks to the drunkard you will also repair the Gauss and get links to it. Cardan is also the only one who can make it possible to run in the egzoszkeleton (screen), however he will need calibration tools to do it, so you must first get to the Pripyat sector.

The second engineer worth mentioning is Navikov (point 28 on Jupiter map), who can be found in the scientists bunker. He's the only one who doesn't demand tools from you. Unfortunately he can perform only certain modifications to your armours and helmets and only after you complete a couple of missions for the scientists.

The last useful mechanic is Nitro (point 6 on Jupiter map). He needs tools and is the only one able to fully upgrade your tactic helmet.

Call Of Pripyat Complete User Manual Guide

As a matter of form, it's worth to mention about lieutenant Kirillov (point 3 on Pripyat map). He won't improve your equipment but will repair it for free and will give ammo and grenades from time to time.