I followed a TS spider with Eibach springs and kyb shocks. It was bouncing the whole time.
My spider on the other hand has uprated Bilstien rear shocks and doesn't bounce down the road but feels planted.
This is why I recommend you to fit uprated shocks.
As I've posted before:
Rears I've got Eibach & KYBs, just sold one with Eibach & Monroes, got another with Eibachs & Koni Sport. I've got a few with std springs & KYB, also a few with std & OE rear shocks.
In my experience most of the bouncing feeling comes from the fronts, especially if not new shocks + the lower the spring the harder & bouncier it becomes.
Admittedly most of my suspension experimenting has been with V6 GTVs but I've had plenty of TS Spiders. The vast majority of these have been on std shocks & springs....for a reason....comfort. I did have one on FK coil overs that surprisingly was actually quite nice. I hated these on a V6 GTV though.
If the OP wants a lower look then he'll have to put up with a harder ride & it is noticeably harder.
KYB rears would be fine but a full set of Koni STRs might be a sensible budget option.
Unfortunately there's only a couple of ways to find out & that's to suck it & see or trial & error......or test drive someone else's already lowered car.
I find most people with lowered cars will say theirs feels nice but then they would. Me, I've got various spec suspension on my GTV's for sale & IMO the best for everyday use & comfort is std but I'll happily sell one with Eibachs if that's the look the customer wants.
I'm not saying Eibachs are horrible, for a quick blast they're good fun, but after a while they become 'annoying' compared to std........whatever shocks you've got.......they're even harder than 19" wheels with 35 profiles which until you hit a pot hole are lovely.
To the OP: if you're still running 16" wheels on 205/50s then just by changing to 17s on 225/45s these will fill your arches slightly more.