I am at only 10k so don't need to worry for a few years, but if I were at about 40-45k I would probably pay for a dealer or reputable indy to assess intake, injectors, carbon build up and make my extended warranty decision based on that. And if necessary get a walnut shell blasting at that time. From what I see At this point, nothing is available that I would want to own. If all hell broke loose I would probably head for either a VW or Audi TDI. Meanwhile I am investing big bucks in my D. Slightly unnerving, but oh well. I might get hit by a bus or die of some surprise ailment before then too. Sorry to be macabre, but am a bit older than most of you guys. So I don't get as frazzled by this stuff as much any more.
Mods-Etc: Quaife LSD w/VAC finned diff cover, M3 Rear SF Bushings, M3 sways & OEM Susp Front/Rear Cmpnt Kits ('cept strut brace), GC Caster/Camber Plates, AC Schnitzer M3 Sport Springs, JRZ RS1 dampers, JBD 100%, Goodrich SS brake lines, non-stggrd APEX ARC-8 18" wheels with Nitto Motivo tires (winter OEM 17" wheels and Blizzak LM-25).