If it needs EGR added it takes 5 minutes to drill the passages even with the head on but make sure that #2 exhaust valve is fully closed while drilling so nothing gets in cylinder. Usually the NON EGR heads already have the bolt holes drilled and tapped but it still only takes a few minutes to do that also if it is a problem. I have not paid a whole lot of attention to what years and aplications did or did not have EGR I just add it if I need it and block it if I don't.