Should I add subs from old car?

Ive got some Rockford 12" P2 punches dual box from the old cobalt. I personally want to get them wired to the SS. I'm a big metal guy and miss hearing those blast beats vibrate the seats. Everyone close to me says not to do it for differing reasons.

Anyone have any suggestions, would you if you had the box already? I am also worried about possible rattles from the vibration. In the cobalt the interior panel above the trunk and below the rear window vibrated and I had to add some foam underneath. Very easy fix but a fix none the less that could show up, and with a much more expensive car.

Phil