I agree with Jason: I don’t think that they make an adapter for this as I’ve looked on their web site before and could not find one.

I would seriously consider each unit having its own GPS Receiver. Not only will each unit than be able to update the boat position at the faster rate but it will make all waypoints that you mark on the sonar Views more accurate as well. Since you will be getting a new GPS Receiver along with your new Si unit you won’t have to buy anything else. If you need a diagram on how to connect them both up with the InterLink, just let me know.