You will get poor emissions results before the engine warms up. It basically re-runs part of your exhaust fumes to for re-burning and smoother cold starting.
What I did was went into the ECU and basically made an override. This way, I can disable the EGR, but still have it on for cold mornings, emmissions tests ect. Ill let you know how it works this weekend once I get the Head back and the engine re asembled.