Have the intake scoped and look for carbon build up, if so then HERE is the DIY. People do it as basic maintenance on the cars every 50-60k. Have not tested or carry BSH catch can so I cannot comment on that.
Dont know about the 335i as on the MINI forums we just deal with MINIs , better to ask on the ECS on the BMW specific forums.

 

Just about every 50,000 miles the intake valves need to be cleaned to maintain optimum engine performance. Once the build-up reaches the maximum tolerable level, the engine will begin to run rough and misfire. You may have a rough idle, poor acceleration, stalling or single to multiple cylinder misfires. If you have any of these symptoms, check for valve residue build-up. We have a carbon cleaning DIY (image from tech article below) that you can check out that goes over a great process for your MINI.

Check out the M7 Speed "Exact Fit" Oil Catch Can as a great alternative here.

For your 335i, yes, you should do a clean up as well. People commonly have a CEL or complain about poor fuel economy, boost issues, misfires, which can all lead to needing to do a clean up. We are also BMW tech friendly so let me know if you need anything else for your 3 Series.

 

Wow you both have awesome customer service thanks for the tips

 

You are welcome.