[kpham]

I have a E60 535i with the N54 engine for about 10 years now and after 60K miles, I started to have sluggish accelerations and lower MPG's. I took it to my mechanic and he suggested getting a walnut blast procedure done to clean my valves. After he took off the manifold, he showed me the caked on carbon that built up over the years. After the cleaning, the car was like new again.
I'm sure carbon build up will occur for the S55 engine as well, but would installing a catch can really be effective? Has anyone here have it installed and how much gunk does it really catch. I'm sure the cost for a walnut blast is twice as much on the S55.