Problem with acceleration

[Cloudsurfer]

The light flywheel totally transformed the car. It gets rid of the typical German sluggish rev response and makes the motor MUCH more rev happy. Heel-toe downshifts are a breeze after the change. I swapped the flywheel on my last M3 too, and it, too, made a world of difference.

As to the noise, if you swap out the factory dual mass flywheel for a lightweight (which will be single mass), you should use a sprung centered clutch disc to allow for some damping in the system. This will eliminate most of the chatter.

If you are getting seepage, then you're likely going to need the RMS seal. If you're on the original clutch/ flywheel, I would almost certainly replace it after that many miles. Call it cheap insurance and a job done right. If you're not doing the job yourself, you're not going to want to pay the shop to pull the transaxle again after swapping just the clutch. While in there you might also think about updating the IMS seal (not the IMS itself) and using the new encapsulated bolts.

As to updating the IMS, unfortunately this requires splitting the cases of the engine, so it's only something that can be done at rebuild time.