I agree with Jerry that towards front and just so you can see down side is best for all conditions, but post still is in view from drivers seat that you have to look around at times.
I have an Entegra owner friend that is from Sweden and just returned from visiting his mother there. Evidently in Europe they use an entirely different mirror than you cannot get anywhere in the US. It is a full piece convex mirror that fits inside the housing we all have with two mirrors in now. He has installed them in his Entegra and has 2 sets for me when I get to his place to change out. (extras for if we break one) If you have the three piece mirrors, 2 in the housing and one on top, this replaces all of them and you do not have to continually look in all three to see what is beside you. One mirror does it all much more plainly and all in one look, you see everything at once.
When I get them installed early this November I will have more info on all parts and details and will post.