[Perfectlap]

The installation fee of lowering springs really makes me think they are not a good idea.
Its a crap shoot.
Once the car is dropped you are stuck with that ride height.
If you HATE it then you will have to get her back on the lift and swap out something else you do like. That's two install fees.
And one man's paradise is another man's night mare. Even if you drive the same I wouldn't put any stock into what another driver has to say about his ride quality.
Driving an expensive Sports car needs to be a precise experience.

My advice if you are set on lowering the car: Billstein PSS9 Coil overs.
Expensive but the 9 compresion and rebound settings and limitless ride height
combinations will turn your Boxster into a land shark. The only draw back is that you might get bumped up one notch into the CaymanS/CarreraS class and you'll have your work cut out for you to place above mid pack. Short of that Go to a local PCA event and ask to ride with a Boxster owner who opted against full coil overs and just went with the Eibachs.

also smaller/lighter wheels will make a bigger difference then a 1" - .5" lower ride height over a lap. I have the 20 pound carrrera 5 spokes with R compound tires an excellent combination. Anything under 20 pounds is a big help. But lighter tires is more beneficial than lighter wheels. Reducing moving weight is key.