Have to agree with Ken, forget 18/19 if you're worried about ride. Also agree more grippy tires are available although I think most of these tires in the extreme performance category or too hard core for someone that doesn't track the car. You'll most likely NEVER see a benefit on the street, but you'll put up with constant road noise, a harsher ride, and much worse wear.
I disagree on the spacers. They completely change the look of the car. When I went from stock suspension to slightly lowered with soacers people's reactions were vastly different. I'm not saying that attention is good but clearly everyone saw the car differently. I wondered if it was even the same car.
I also think your spring rates with something like a KW V3 at 350# rates really improve the handling and they hardly change your ride quality. In fact having been in a car with Bilsteins and OEM springs and also with V3's I'd say they ride about the same or I would even give the edge to the KW's. It's just a superior damper. They have a lot to do with the ride quality. As much as or more than the springs. If you have the OEM spaghetti sway bars, which you do, then you can really benefit from a bit higher spring rate. You won't know how much lean the car has in corners until it's gone. Or how responsive the steering can be until you get what makes it so. I've been on prime a long time and I started out like you. I tried a lot of things with people's advice who knew more than me. Everything I'm posting here is absolutely from first hand experience on and off the track. IMHO you are better off with a slightly stiffer suspension and less hardcore tires. I think the tire has SO MUCH to do with it and I fully get that now because I'm riding on pilot super sports that are just fantastic with ride, noise, wet weather, and wear. Yes there are gripper tires out there but I'm on a suspension that is on 800 pound springs up front and 550 pounds rear. Quality dampers and I have a great ride. What makes your ride bad are tires with these ultra stiff sidewalls. I'm honestly not sure what is available outside extreme performance in 17/18 anymore. I haven't followed. But the extremes are all designed for the guy that goes to the track on weekends and doesn't want to go to slicks.
It's important to make the point here.... Half the guys on this forum run these and so did I. I've ran the hardcore bridgestones, falkens, Dunlop start specs, Yokohama AD08's, Nitto NT01 R comps. I honestly feel most of these are more "feel good" tires than a real, actual benefit. Because they give up way too much on the street, and require a very skilled and experienced driver to shine on the track. Billy Johnson was talking to me once and said "be honest with yourself. Will you really be faster on a harder core tire than the pilot super sport?". And he was right.... Going to the extreme is... Well... Extreme. I'm rambling but if it was my car it would be a set of KW v3's instead of the Bilsteins and stock springs, soacers, and something less hardcore than extreme performance tires. Eventually I would add a type R front sway bar. I think for you that setup is perfect.