[lkchris]

Extractors are the way to go, but the car has to be designed for it.

The Boxster isn't.

Most of the cars designed for this have oil filter easily accessed from the top, too. Again, the Boxster doesn't. Somewhat the nature of mid and rear engine configurations, perhaps.

FYI, the extractors used at a Mercedes dealership don't involve a tube down the dipstick tube, but rather a tight seal at the top of the dipstick tube. Better, but more expensive and not universal.

When the car is designed for it and the equipment is good, extractors get all the oil out.