Helix is proud to announce an introductory offer for walnut shell cleaning of your intake ports and valves. As you have probably read, this is a major issue for DI cars (like R56 and newer) which robs the cars of smoothness, power and idle stability after as little as 30k miles. The dealers offer this service for $7-800. We are currently offering the service for $499. Here's a N54 with 50k before: And after: