I purchased the GRT EFIS at Sun n Fun for my IV-P. I attached the magnetometers to the roof of the baggage compartment and the ADC/AHRS to the forward center floor nearby. This allows easy access for the flight test phase.  The magnetometer calibration worked well here. The ADC/AHRS is easily accessible for configuration variations in the pitot and static line connections, wiring harness additions, and attitude adjustments.

 I have about 70 hours experience in this airplane over the last 4 months, since I purchased it with 35 hours TT from West Coast Rockets. I have suspected a pitot-static calibration error. With water manometer and EFIS calibration I have about a 5 knot error on the mechanical airspeed gauge and another 7 knots error in the static system. I have a single static port mounted just below and forward of the corner of the baggage compartment door. I plan to add additional static sources. Does anyone have guidance for this on the IV-P ? This is another reason for the initial mounting of the ADC/AHRS in the baggage area.
Thanks
Bill Miller, MD
Naval Flight Surgeon(ret) & Test Pilot
USN TPS Class 92
N330FF 70 hrs