Group N Oil Restrictor (S50B30)
Genuine BMW Motorsport Group N Oil Restrictor, for S50B30 (Euro spec) only.
When used at high revs for prolonged periods, like during track and race use, the S50B30 has a tendency to over-fill the head with oil, resulting in excess oil in the breather system which can cause misfires and running issues.
BMW developed and used this oil restrictor in Group N racecars as a very effective fix.
Available on back-order