I would like to not run a front plate, but I have not gotten a feel of how long it would take me to get pulled over around here. They seem fairly strict.
I would be keen on some 18" 5-spoke Carrera's but I am also fond of *cheap* tires for the 17's for the amount I plan on driving it.
As for lowering it, I have enough trouble in the 944 with speed bumps, I don't want that in the Boxster. Granted the 944 has maybe 3" of ground clearance.... maybe....