I would think about a set of Koni FSD, if they are available, as they are "self adusting' to road conditions. NB I have Koni Sport adjustables on my 147 and they are very good as well but from what I have been hearing not as good as the FSD. Bilstein and the Koni sport adjustables are supposedly comparable.
This is the comment by someone (KrisW not sure if they post on AO but I am sure they won't mind
)on italiaspeed forum who has them fitted to his 147.
"Okay, as mentioned previously, my 147 now has a set of Koni FSD
shocks on it. The reason for doing this was that I find myself driving far longer distances than I did previously, and the standard suspension is a bit harsh for these journeys -- especially over rough road surfaces.
First impressions were that the FSDs were way too hard - harder than the shocks I’d had taken off, in fact. Driving out of the garage, I could feel every bump on the road. However, with a bit more speed, it was as if the road became smoother, and at motorway speeds the ride was amazingly good.
Describing the setup is difficult - the roadholding makes you think it’s hard sprung, and so you almost expect to feel the bumps in the road, but they’re not there: in fact there’s none of the juddering you get with hard suspension setups at all. At very low speeds (<30km/h) some of this lumpiness comes back, but no worse than the stock suspension dampers, and at normal driving speeds it’s gone.
So, €650 for the set of four dampers, and €250 for fitting (my insurance company insisted on a main-dealer fitting). Is it worth it?
Short answer for me is yes. The new dampers bring the ride to the level of the 159, but with better handling. Considering the costs of trading up, even at the bones of €1k, it was worth doing, for me."
I also found this..on a BMW but.....
KONI FSD Dampers Improve Handling Without the Traditional Sacrifice in Ride Quality