depends on the model, my early 130 sport is OK is it the ecu? different on the FR?One thing you should know though is, that the Engine management light will come on if you eithe reduce the flow of the EGR or take it off.
My car has the engine stutter on the BLT engine code and the dealer are refusing to acknowledge it....
With regards to winding back the EGR settings, the downsides are to the environment. The EGR valve is there to help prevent the engine producing as much nitrogen oxide and dioxide, particularly when not running at peak power.
i think if it produced nitrogen oxide (nos) they would try and recirculate that back into the system will go like made then!
Bollox to the enviroment, im not bothered, im gonna have a petrol car next year, and im gonna make sure it pollutes **** loads, especially when you have to pay £190 a year in road tax.