I think the carbon buildup is worse, the CCV system in the n63 is an absolute joke. I ended up installing catch cans. The really difficult this is while the turbos and exhaust are a breeze to work on, it's the opposite with the lower intakes since this is a reverse flow engine. It is impossible to remove the lower intakes to get access to valves without pulling the engine or removing the heads with the intakes attached while it's in car like I did. I don't have a lift so didn't have a choice and when I saw how badly pitted the exhaust valves (150k on the clock, and when I got mine the turbo return lines were nearly blocked so it was burning excessive oil that helped with pitting the exhaust vavles)were on a borsecope, I knew I had to pull the heads anyway....that later tunred into a full port and polish job.... I got mine off eBay from Midwest tool. They have been amazing to work with. 299 rental plus 800 deposit for two weeks, only 70 dollars a week to extend it. I'll be returning mine in about a week (had it for months due to work and life interference)