If you are a filter nut then look here.
http://theoildrop.server101.com/cgi/ultimatebb.cgi
A filter company usually wants to have a complete line of filters. If it is for a car that they do not make a filter for then they rebrand it, and sell it as their filter when in fact it is made by another company. Just like Porsche does.
http://people.msoe.edu/~yoderw/oilfilterstudy/oilfilterstudy.html
No clue if this is going on with a Boxster filter.