Most of the 986 stereos are pretty weak sauce. The Bose was the best but still mediocre compared with the excellent Mark Levinson sound in my wife's Lexus.
Lexus Mark Levinson Audio Systems | Mark Levinson
I have resisted upgrading the stock stereo for fear of missing out on the symphony coming from the tail pipe.
When I want studio reference quality in the Boxster, I bring these:
Amazon.com: Shure E2 Sound Isolating Earphones: Electronics