Ive had vagcom on looking at the temps, 4k revs at full throttle there is over 1200C exhaust temp - plent of NOx's being made there im sure!
I know smog isnt a huge prob in the UK but anything to
help folk that have breathing problems and im happy with it. Knowing plenty of asthmatics (Fiancee included) im sure they are thankful for our few HP loss in return for improved air quality!
The EGR recirculation is cooled via a heat exchanger by a med temp water take off from the cylinder block. This water then goes to the heater matrix for the cabin heat then to the main radiator.
Blocking the EGR may mean the heater performance is reduced as the water temp will be about half way between the flow to and from the radiator as it wont get an extra topup from the EGR.
Anyway, if you want a few extra HP, put the AC off and your lights, heated seats etc and empty the boot.
Stuart