I just got an 09 fJCW Clubman and have put about 2.5k miles on it. Runs fine and no concerns. I've been busy modding it(as much as I can find time in a warm borrowed garage anyways) and was planning to put an OCC on. However, someone mentioned that I should get the walnut blasting done just to start on a clean slate. Vehicle has no issues(then again I don't have anything to compare it to, as far as a perfectly clean fJCW anyways) and I thought I should just install the OCC and get the walnut blasting later, but then again do not want it done too late(symptomatic and possibly already damaging parts). Odometer reads ~27.5k miles.

Tried searching but everyone is getting it done when symptoms came up.

 

I'm at 75,000 miles on my '08 MCS with the factory PCV setup and have never cleaned the intake. I haven't had the manifold off to look down in there (yet)....I would imagine that there's plenty of carbon/gunk at this point, but I haven't had any issues or symptoms to date.

As I understand it, the walnut blasting treatment is not all that cheap ($300-$400). Unless you just have money to burn, I would recommend you just wait til later down the road. If you are installing a catch can, you may not even need to worry about it. Spend the cash on some other mods....or take a roadtrip and enjoy your car. Just my $.02