The lower your cheap coilovers are the worse the ride will be, so if your raising it a bit it should start feeling a bit better, no doubt your running rubber band low profile tyres on the 17's as well so they fit which won't help with the ride. ive got 16's with 40 or 45 profile tyres on mine (can't remember) and cheap jom coilovers not running too low and i can't complain about the ride.
Before you start spending a fortune on new suspension, just raise the car to an acceptable level and see if it improves any. If not, its decision time, the expense of spring/shock suspension or smaller wheels with a bit more tyre profile.