Was your EGR and manifold pretty clogged up? Maybe the better power delivery is down to merely opening up the airways rather than the delete itself? Still going to give it a go myself soon but using the blanking plate method and therefore maintain original appearance for MOT time.
Ian, from the info on here it seems only post 2002 models give a check engine warning light. Easy way to check is to pull off the EGR vacuum pipe and plug it with a small bolt or something. A couple of engine cycles should be enough to bring it on.