I am confused about the EGR debate. Some seem to swear that blocking it does the engine a lot of good. It is really only for environmental reasons, nothing to do with performance they argue. The other school of thought argue differently, indeed some claim a clean EGR has improved their MPG on diesels. I also read on youtube that the I-CDTI engine was designed with EGR technology in mind and that it in effect has two of these. My mate has blocked his on his BMW 525d and is all excited about the increase in performance. I am tempted, but thought it wise to ask on this forum first. Can anyone shed any light? Thanks in advance.