I have been thinking the same thing. When the rear spoiler comes up on the freeway it makes the front end feel light. ( I had the same thing with a Miata and I put on the small factory front spoiler and it made it feel much more planted!)
I have been thinking of putting some weight in the front, (I used to do that with my Beetle) or seeing if there is an inconspicuous front spoiler available. So far only seen this one for 986...
97 04 Duraflex for Porsche Boxster G Sport Front Lip Under Spoiler Air Dam 1 P | eBay
Any other ideas?