If it's crashy, the original dampers are tired. The factory setup is soft springs with stiff damping, so aftermarket springs (usually twice the spring rate) soon kill off ageing OEM dampers.
Even when new they never rode like a Bentley, but there shouldn't be any excessive crashiness or wallowing on fast B roads. So you could try a set of new OEM dampers (don't use cheap patterns) or get a kit like the ones suggested.
There's no such thing as the perfect setup though. The majority of people don't drive the car on a wide enough variety of roads to build a full picture, so spec the suspension to suit your daily driving. i.e. stiff if the roads are smooth, and soft if they're sh1te.
I would recommend, in order of tastiness:
Cheese sandwich OEM dampers with new OEM or mild spring uprate.
Ham and mustard sandwich Racingline kit if you want daily smoothness at a moderate pace.
Beef and Horseradish sandwich Bilstein B12 if you want to dial it up a notch on the B roads.
Premium fillet steak adjustable damping coilovers if you want the best of all worlds.
Obviously the price of these will differ drastically depending on brand, spec and lifespan expectancy.
I've tried all of the options and I went with fillet steak and haven't looked back. 90% of a suspension kit is all about feel rather than improving outright cornering speeds, since that is governed by tyre width and compound, but if the new suspension makes you feel more confident, you can push it harder......which is where the faster cornering comes from
