Dude, dont stress bout the mileage. some on this forum have had their cars for close to 300k km with no stress. the '02 would be the 135kw version, which was awesome.
The 6 cylinder diesels are generally reliable. I would advise you to get rid of the Swirl Flaps as they do break and when they do the damage is catastrophic.
Please enjoy your stay on this forum. I see that you joined last year. but welcome, anyways.
+ 1000 on Tunetech. Ive alse been using them for a lil while now, and would not send my car anywhere else in JHB.