whats EGR?

well

exhaust gas recirculation something that you dont really need

It's a valve that pumps hot exhaust gas into the intake to speed up the warm up of the engine to reduce emisions or something like that.

Like stated above, its stands for Exhaust Gas Recirculation. If you have a visual inspection to pass emissions - you need it. It is designed to recirculate exhaust gases into the intake under certain driving conditions. It helps burn off excess fuel, cools the combustion chamber, and helps prevent detonation. EGR also allows for more spark advance, and a little more power with a properly tuned engine. You can run without it and still pass emissions (non-visual). EGR really only affects your NOx emissions - which are usually caused by excessively high combustion chamber temperatures.