what type of car are we talking ?? as far as lowering I myself see no need to go lower than 2" at most.
a lot of people will tell you go with
Tein or JIC, a true adjustable coilover set-up.
cost $1000+
ride, unbelievable cornering very firm suspension, bruise your girlfriends ass over every bump.
or you could save a little bit of money and look for some
KYB agx shocks w/ a reputable spring ie. Neuspeed, H&R etc...
adjustable shocks only.
cost under $750
ride, great to really great cornering, semi firm, a lot less bruising of your girlfriends ass.