http://www.peachparts.com/shopforum/tech-help/22940-head-gasket-radiator-w140-post117864.html
Leak seems to be gone, it there ever was one!
The chip is ok but I don't
try to drive the car very hard, so I 've removed it. The KN filters are still there and seem to be just fine. I don't know whether they
actually get more air into the engine!
My conclusions are just subjective, so need to do a search from some more qualitative reviews from users who have tested them on a dyno.