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What model unit are you asking about this for? That may be a typo on your part as we do not have a “199 si di” model.
If you were meaning the 1199ci HD Si model unit, then yes I recommend adding the XP-9-20 inside-the-hull (aka: “Thru Hull”) transducer and the AS-Si-DB-Y transducer if that is a planning/lifting type hull on your Ranger.
There is a somewhat smaller Si transducer that is made for the trolling motor (XTM-9-HDSi-180-T) but you will lose the 800kHz Si/Di sonar capabilities if you use it.