If you don't have to run a EGR leave the mani on. No EGR is illegal in 50 of the 50 states in the us. But.. it all depends on your local emmisions laws. If they do any under hood visual inspections you'll get bagged if they don't then all the power to ya. If you are going to swap them do it before the motor is in its a real PITA to do it after.