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Our situation is this.. We recently went through a major redesign that included a significant change in content and URL structure. This of course cause a significant increase in 404 from our search traffic. In an effort to minimize those 404s we requested that Google remove certain URL directories from their index. Doing this resulted in a 90% drop in the number of impressions we were getting from search. My question is this, is it better to allow the 404s with a good landing page that explains the changes or better to remove the bad urls? Much thanks...