Loud ticking. MB dealer replaced fuel injection system, still ticks

Hi-I bought an E350, 2014, in January. It replaced an 1999 E320. The '99 had a fantastic engine that quietly purred. The 2014 has rather odd sound, more like a Chrysler than a mercedes, often described as clanking. I've done a great deal of research on this and it is caused by the direct injection fuel system, some 28 micro fuel ports in each cylinder, pumping in a fine mist at 2500 psi as opposed to the former fuel injected engines with around 25 psi. Some engines seem to be a bit louder than others and often have been described as sounding like a diesel engine. Apparently this is all normal. Why some seem worse than others is a mystery. If anyone else has additional information on this, please post.