The spacers do not lower the car but put the wheels 15 mm futher out of the housing. The lowering of my car is due to the PASM option.
The spacers are not offered as an official option in the Boxster brochure - this probably due to the fact as such spacers often are not allowed according to the law.
When adding spacers, you MUST use correspondingly longer Wheel Bolts. In other words, if you add 5mm spacers, you need 5mm longer Wheel Bolts, 17mm spacers, 17mm longer Wheel Bolts etc.
Usually, they are included when you buy the spacers. If not, a Dealer can supply them to you - spendy!
Don't scew around on this one - it's what keeps the wheel on the car!
I was wondering about these myself, what do they do exactly to handling etc?? is it just aesthetic? as in filling out arches or is there handling advantage?
There can be a slight (read very slight) handling advantage when on the limit.
But what you are essentially doing is widening the track and so increase the potential for Bumpsteer and Tramlining at all speeds. Not usually a great trade-off.
Additionally, widening the track also increases the potential that the tires will kick-up stones which will chip the paint surrounding the Wheel Wells and especially the Side Intakes (because the Bodywork flares slightly there).
Most people doing it are justifying it as a performance tweak, but the main advantage is aesthetic. IMHO, 5mm is the biggest spacer you should use. You get some of the aesthetic effect and minimize the negatives.
Ooops I am a little colour blind I would have gone for the GT myself (sort of in between Arctic and Seal I guess) but couldn't justify the moola on that option. Beautiful car though Enjoy it in good health