lowering springs are generally stiffer so its going to ride a bit rough. even if you get the cheapest of the cheap shocks it may help because well the springs are stiffer so you may want to to bounce just a tad to lessen the impact force you will feel.
i have gabriel ultra shocks on my truck. they said they were ment for light trucks and suv's and didnt htink anyhtign of em but when i went to install them they were a bit bigger diameter and now it rides stiff as a brick. i was going about 65-70 on a chicago insterstate (really bumpy) and while the ride wasnt bad if i stopped beathing the bumps would make me bounce up and down enough to where it would force air in and out of my lungs... it was a weird feeling...more of an annoyance than anything.
The bottom line is that anytime you start messing with springs and shock absorbers, the vehicle is going to ride differently, and sometimes in unpleasant ways.
I had a 2004 STi that I had installed Eibach lowering springs on. My wife had difficulty even riding in the car after that, as the change in bounce rate just did something that messed with her. It didn't really ride that much differently, but it was enough to cause problems even though she could drive it without having issues. I never had any issue with it and felt that it rode just fine. It was a subtle change, but significant nonetheless.