I have the same car (2003 non m/sport) and slightly more km's (225k) and was wondering about chipping it for a long time now. What kind of driver are you? What i am trying to determine is if you are gentle with the car most of the time and only use the extra power for emergencies, will the car last as long as a car without the modifications?
The gearbox is a big worry. Must say that the gearbox on my car has not given a days worry. It is extremely smooth (if a jerky gearchange is anything to judge a failing gearbox) and i hope to get a lot more mileage out of it before it breaks!
Mods on my car: decat, deflap en egr vacuum plugged. Am very happy with the power presently but am always on the lookout for ways to increase the torque!