there are aftermarket rolls grilles for the '91-'93 DeVille.... chrome or gold.... nice hefty $650 or so too..... customcaddy.com (or ebay)
personally I like the factory grill..... the rolls pimp grille only looks good on something like my mothers '89 Borugham, where the huge grille is backed by a huge car... (plus I like the grille on the '91-'93, especally the '93 how it has the bold look) <---- not regular honey-comb type stuff....
change your strut towers to sir bags. you have a air tank in the back of your car. You'll have 4 switches to change the amount of air in each air bags. You can raise or lower each wheel. www.airride.com
airride can be cool, but if u push ur car hard id advise against it.......also you can tint your tailights (i can hook you up with a guy who will give u a fair shake) and be careful with ur new rims.....you wanna go light!!!