I have a HELIX hooked up to my Terrova. It's a great combination. If you don't plan on following a contour or asking your TM to go to a Waypoint then linking them isn't for you. I can get you whatever you need at Krenzer Marine in Sodus. Whatever specific questions you might have I can answer. I've used both Terrova and Ulterra. I can tell you pro and cons with both. I'll also be at the Syracuse boat show this weekend working a marine electronics booth with Krenzer Marine. Just ask for Rick.