I have a Gen 2 HDS 5 in my dash (it came with our 2013 Ranger) and as stated earlier, I added two 900 series Humminbirds. I do think the Lowrance 2D sonar is more sensitive, but part of that is learning how to set up the Humminbird. IF I'm not mistaken, the HDS 7 should have a built-in GPS antenna, so no need for an external puck.