I have ordered  the sports suspention pack for my montecarlo estate... now I’m hearing the montecarlo has it as standard and others say it’s a standard fit to the estate rear ! I have also been told that it’s neither and 15mm lower ... I’m confused ... what’s what ? Is it also just springs or springs and dampers? ....help me out pleaaase !!!!

"Sport suspension" is optional and it includes only springs -15mm. IMO they are soft and the car is not enough lowered with them so  don't order "sport suspension", just buy Eibach or H&R springs after you collect the car.