with the 03 boxster is there a after market part to make it possible to lower the top while driving?

 

Don't think the founding fathers wanted the top lifted with a wind load. You wouldn't either, first time you bent a tension bow.

 

oh i was under the impression that the 05 boxster and up it was possible to drop top at up to 30mph

 

Yes you are right, 05, 06 and 07 Boxster can operate the top at up to 30 mph, I do it everyday. It iscleary statedin the Boxster book, even their web site's "Boxster Movie" advertise this too.
Watch this "Sport in Number" film, it shows the top up while the car is moving at about 30 mph

http://www.porsche.com/usa/models/bo...y/?gtabindex=6