I've used DeMan since buying my Boxster in '05 and am very satisfied with their work. Which reminds me that the 90k service is due...
De Man Motorsports
www.demanmotorsport.com
200 Corporate Dr
Blauvelt, NY 10913-1142
(845) 727-3070
(They're in Rockland County, NY, and close to the New Jersey border.)