Many auto makers have been deleting EGR valves. Changes in cam specs and cam timing are used in some cases to give the same effect as an EGR valve. If the motor came with one, run it. Besides, if you live in a smog state it must work to pass a smog inspection. Disconnecting it can cause it to stick shut and not work when you need it. It can also cause a check engine lamp. On, and on and on...