The big question is do you have the factory BOSE/MOST system. If not, there are lots of options. The original factory system (not MOST) came with the subs in the door panels. This is what mine had and I decided to keep that configuration, but with all new components (HU, amp and all speakers). I modified the original door speakers housings to fit a 6.5 Kicker sub in each door. Then I put new speakers in the dash and in the rear parcel shelf storage compartment (again, not a BOSE unit). Here is the link to my process. I've since upgraded the HU to a Kenwood with AndroidAuto.
Build link
2004 Porsche Boxster
2003 Porsche Boxster S
Threaded Mode
