I have setup alot of boats w Hbirds, and on even my own boats the 2D sonar thru a US2 w a DI model like my 958HD DI is SUPERB compared to a 998/999 family of Hbirds. I had a network on my big boat w a 958HD DI on the bow and a 998HD SI on console and if I had full screen 2D sonar on both units and used a network transducer either thru the terrova or my 2D sonar transducer on transom w a Y cable the bow unit was far superior in detail and image. Why are the DI units so much better in 2D sonar images? a regular 958 does not have the same quality, its equal to the 998/999 images, very pixelated and rough looking. When u look at even your breadcrumb trail on GPS screen its not a straight line its tiny zig zags and right angles. On my older 998 non HD unit I ran an oder version of software just to avoid this pixelation, what is the difference in software on the DI models? Also wondering when u choose dual-beam on a DI capable unit that normally shoots 200/455 w its DI transucer what does it shoot thru the 83/200 ducer? just 200 or does it also shoot 83 too? thanks