Just had an audio system installed in my 98 2.5 Boxster and as soon as I picked it up from the shop, the car seemed to have lost all power above 4000rpm. It pulls fine to about this point then it seems to lag and jerk a bit. The audio system involved taping into the vehicle speed sensor and having the battery disconnected but im not sure if this is related.
If anyone has any idea what could be the problem, that would be great.