what dampers are on the car? if its standard with lowering springs then usually they are to soft to deal with the lower than standard springs, and if it is seriously low then maybe have a look to see if the springs have been cut to drop car further. bad if they have been as the struts will bottom out and the pounding will do damage to the suspension turrets.
springs are progressively wound so cutting them will make it handle like poo
17's will raise the car slightly but you will probably find the tyres will get scored from the arches.