What you'll find is that there is a fine line between where the parts you add to gain any handling benefit affect the ride, and add noise as a consequence.
SF connectors:
SF connectors stiffen the chassis. These cars have no frame...(they have "subframes"). The floor itself ties the front and rear subframes together, and that has proven to be a weak link as these cars age. The end result of not having those SF's tied together is excessive body twist, rattles, creaks and groans.
Adding SF connectors have no down side...they do not impact ride quality negatively, and they do not add any noise.
LCA/RCA's:
Your front and rear
control arms will always be a topic of conversation here.
But they are the next area to focus on, as they are directly contributable to sloppy handling. All aftermarket brands use a different type of bushing other than the rubber versions that were stock on that car, and consequently the stiffness of those bushings is measured against stock as a reference. Replacements range from new rubber, to a stiffer rubber, to a polyurethane, eventually to aluminum as you progress through the options depending on what your goals are with this car.
Stock, or a stiffer rubber bushings will yield "new,or better than new" handling character back to the car, w/o any added ride harshness and can be added to your existing factory pieces, but swapping out those rubber bushings in the stock arms is a arduous task. The old bushings need to be burned, or drilled out, and the new units beat, or pressed back in. Several opinions will tell you to completely replace the arms as units because of this,..but the entry level replacements are junk more often than not, are typically Chinese, and poorly made with extremely stiff polyurethane bushings. After that, the quality pieces (from MM, UPR, Griggs and several others ) will ultimately cost significantly more money.
Ball joints:....replace them.
Shocks/struts:
Yours will need replacing. This is another "name your poison" topic. As there will be many recommendations for brand preference here. Several guys have Bilstein, some Have KYB, some have Koni, which all have a performance benefit with regard to adjustability, or at least a more performance leveraged shock valving. Other than that, you have the din of stock replacements out there...IMO,..unless you have any intention of going after "significantly other than stock" handling, a stock replacement set of shocks/struts is all you need here.....Guys that street drive a set of Koni's get no benefit from that shock other than the warm and fuzzy they get from the knowledge that they have them. A set of dampers intended to increase handling performance, ALWAYS contribute to a stiffer ride.
Springs:
Lowering springs will ALWAYs have a negative consequence in ride quality. The car looks better w/ a lowered stance, but the consequence of a shorter spring that keeps the car properly suspended is additional stiffness. That stiffness is a desired quality when talking about handling, but sucks ass when driving over a rutted road. Lowering springs open the can of worms,......as that changes
suspension geometry in the front end. The correction requires caster
camber plates (not necessary if you didn't lower the car). A lowered car requires that the tie rod angle be dealt with, as "bump steer" becomes an issue. Bumpsteer occurs when the car hits a bump and because of the change in front
suspension height, the intersect point geometry has changed, and now the tires "steer" as they travel through that arc radius. ( Again, not necessary if you didn't lower the car).
Low profile tires:
A 17" or 18" wheel will dramatically affect handling characteristics over the stock 15-16" wheels the car came with.
As the rim size increases in diameter, the tire sidewall decreases in height. The shorter the sidewall, the less impact absorption the tire is capable of dealing with. Again, just like a lowered stance, a larger wheel looks better on these cars, and there will be a handling benefit gained from adding a set. But again at a trade off.
These 6 things all need to be addressed if you want to return or improve the car's handling/ride quality.