how much of a difference does having the egr spacer make in economy as compared to not having it. i still have my egr spacer but when i went to the dyno tuner he pulled the vacuum line off it and did something to the computer so i wont get a check engine light. is this hurting my fuel economy. with nothing but city driving (absolutly no freeway) i used to get 15mpg around town keeping the rpms at about 2800 when i shift. then i put on a sc, went to the dyno tuner and now i get 8mpg with the same driving. i can baby it and get about 11mpg but thats no fun. also, untuned before the sc i was making 225-250rwhp tops, with the sc im making just over 400rwhp. i know at 0 vacuum and under boost the egr is closed and wont hurt top end, but is having it closed when idling and cruzing hurting my mpg?