First off, amazing job with the DIY. I had been concerned about the smoke issue late last year for my '03 S and bought the AOS from pelican parts but hadn't gotten around to installing it. Yesterday the smoking on startup and while running has become extreme so I intend on installing the new AOS.
However, Pelican has two AOS units for sale. The one that I bought (Oil Separator, Boxster/Boxster S (2003-04):
http://www.pelicanparts.com/cgi-bin/smart/more_info.cgi?pn=996-107-026-01-M100&catalog_description=Oil%20Separator%2C%20Boxster%2 FBoxster%20S%20%282003-04%29%2C%20Each
And the one that resembles the AOS in your instructions (Boxster/Boxster S (1997-02) up to Eng # 65X01419):
http://www.pelicanparts.com/cgi-bin/smart/more_info.cgi?pn=996-107-023-04-M100&catalog_description=Oil%20Separator%2C%20Boxster%2 FBoxster%20S%20%281997-02%29%20up%20to%20Eng%20%23%2065X01419%2C%20Each
Anyone have an idea if the install is much more difficult for the 03-04 AOS?