Montague: thanks for confirming the existence of the swirl flaps; I have learnt something.
Agree too with your comments on the EGR valve, something I have just had to replace to get rid of the MIL that came on a couple of weeks back. So from what you say, that can be ditched and blanked off without any remapping or suffering of performance. Maybe “illegal” as far as MOT is concerned though…if it gets noticed that is!