Some people may know this, but some people may not. Just read an article related to the EGR valve. The reason it was interesting to me was the fact that I have blanked mine off and although I have read that this is ok to do, it could possibly cause a lot of damage to the turbo. When the gasses are being recirculated they cool down the ehxaust gasses which helps to cool down the turbo, blanking it off could slowly fry the the bearings in the turbo. I have now removed the blanking plate and shall make a point of cleaning the EGR and inlet manifold maybe once a year. Also the info explains about that if the valve is faulty it can stick open and cause hesitancy and power loss and if it sticks closed can lead to turbo failure.
I blanked mine off as I was concerned about it getting full of baked on carbon deposits, but to me taking it off and cleaning it is cheaper than possibly a new turbo.
Hope this info is helpful.