Not an S, but my car is Arena Red and has a black interior. It's the "full leather" interior which is much nicer (and much more rare) than the usual "basketball" rubber/plastic interior.
http://986forum.com/forums/boxsters-sale-wanted/65775-norcal-2000-boxster-arena-red-ln-ims-hardtop-litronics-full-leather-etc.html
