Drove an M5 today and noticed the susponsion felt stiffer and noticeably more responsive than my '99 540i 6 speed and was not harsh. The only suspension mods I've made to the 540 are strut brace and rear sway bar. So would anyone suggest that I go ahead and do some Dinan suspension mods (please don't suggest that I get the M5 - that's already being discussed).