Just a question on blanking off the egr, as the fuelling etc is set up for when egr opens the extra fuel needed and timing changes to the flame front etc. would it not cause long term damage to the expensive cats for a small gain in power. also would police roadside emission checks not pick this up. NOX kills people by damaging the lung tissue which is why deisel manufacturers are constantly trying to reduce them. as deisels produce much higher NOX compared to petrol almost double i believe, thats why DPF's are now introduced on modern deisels,
Its a bit of a green issue but you could not stand in a car park with deisels running with out harmful effects apart from the smell but you could with a garage full of '92 year on cars with petrol engines and cats fitted So should you or shouldn't block off the EGR.
No, the emissions in reality are closed loop controled thanks to the lambda sensors plus, the NOx levels are still acceptable, its only certain territories that require its fitment (i.e. California).
As already stated, at idle, the EGR valve is shut (and at full throttle), it only operates during cruising.....
Police roadside emission checks cant detect it and neither can the MOT checks (not tested but, some analysers are capable of reading it) as the amount thrown out the back is still very small.