The P0490 is nothing to do with a blocked EGR. It is an electrical problem. The 1.8 Linx engine does not have a problem being fully blocked, both the Euro 3 and the Euro4. The only time having the EGR blocked is a problem, is when there is also a boost leak, like a small split in one of the hoses or intercooler.. It would be best to look up the code rather then guessing that is it due to a plate and that t needs a hole in, as the electrical problem will still be there. Check the link