I have a very nice RV-9A I purchased 6 months ago. In it, there is a D-100 EFIS and D-120 EMS, A GNS 430 (non-WAAS) and GTX327. My autopilot is a True Trak Vision. If I want to be able to shoot approaches and use the HSI along with vertical guidance, do I need the HS34? I miss instrument...