The main thing you will notice (or not if you don't service it yourself) is the oil stays cleaner for longer. The "problem" with doing the egr mod on a new car is you don't really feel a difference because the motor hasn't been run long enough for the egr to cause too much carbon buildup. I blocked my d22 off at around 7000km and can't say I noticed a difference but it seems to come on boost quicker but I can't really remember what rpm it maxed out at before, but I can get 17psi (Max for d22's) by around 2500rpm if I get up it enough. In saying that, even after that many km there was a bit of buildup in the egr pipe but not a lot compared to the older ones..