My charge air pipe from the intercooler is also clean as a whistle, indicating very little blow-by. The intake gets all crudded up from the EGR valve onward.

I've heard disconnecting the EGR vacuum hose on a W210 will throw a CEL, but that's not to say the corrugated pipe can't be blocked off without affecting the EGR valve's operation. Personally, I see no need to disable the EGR, other than eliminating the crap in the IM. The EGR is only open at idle, so it cannot affect performance (eg. turbo boost) while driving.

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99 E300 TD -- sold
01 540i 6 spd