If you want to drop the car slightly and also keep an almost OEM feel then the best set of springs to do that would either be:
Eibach's - Volvo's Own lowering kit - Lowers by 20mm over standard
or
Eibach Pro Kit - Lowers by upto 30mm
Eibachs are top quality springs and you WILL feel the difference without the ride being harsh and too firm. These can be matted with a good set of Blistien shocks too as and when required.