Let me start by saying “Search is your friend……….” There are lots of information on both the IMS and RMS issues.
RMS, or rear main seal, is the oil seal on the rear of the engine’s crankshaft. The M96/97 engines had problems early on with seals that would suddenly spring significant leaks. Porsche at one time was covering the RMS under warranty, even for cars that were slightly out of their actual warranty period. Porsche came up with a revised seal that has completely eliminated this problem. Any year engine can be updated to this seal, which costs about $20, only problem is you need to pull the gearbox, clutch and flywheel to get at it. In general, the cars that were going to have the big-time RMS problem already have for the most part; so it has lapsed into a kind of non-issue. If you are going to have the clutch done, get the new RMS at the same time.
The IMS, or more precisely, the rear intermediate shaft bearing on M96/97’s can fail with catastrophic consequences. Typically, when this bearing lets go, it takes the engine with it. LN Engineering developed a replacement unit and method that allows the OEM bearing to be removed and replaced with a redesigned unit during a clutch change which has been very successful (more than two thousand installed no failures to date.) LN and FlatSix Innovations have excellent websites with tons of information on the subject.
