Somehow the ecu mesaures the values of recirc gases. God knows how as there are no sensors in the exhaust etc. The blanking plate can be made out of sheet steel a couple of mm thick. Simply draw round one of the gaskets you remove, cut out with tin snips drill the hole, dont forget this bit or the light will come on and there you have it. A vastly reduced egr operation for a couple of £ and and hour of labour, it really is that easy. For all those with vag com measure your outputs after you have done it.
Glynn