"So in the Columbia Aircraft there are a few issues that need to be accomplished.  The processor needs to be relocated as far aft as possible.  I have always had to mount it next to the ELT, and then relocate the #2 WAAS antenna about 12 inches aft of its present position.  The WAAS antenna is mounted on a bracket inside the tail about 3 inches aft of the ELT, and close to where the TWX670 processor will be mounted.  If the antenna is not relocated the TWX670 will interfere with the GPS signal and cause about 20% satellite reception.  Also the TWX670 requires the ECS antenna cable, and must be routed in the overhead(with no other wiring in the run).  The antenna needs to have MU Metal installed on the inside of the aircraft attached to the doubler plate.  Noise filters must be installed on alternators 1 and 2, however if the aircraft has the EVADE System installed you can't install a noise filter on the number 3 alternator(which is used only for the EVADE System).  The drop in voltage will cause the EVADE system to fail self-test, and will not function.  There is no way to completely Eliminate noise if the EVADE system is installed and active, you will typically receive strikes at the 10 o-clock position about 150 miles out (however it will not cause the TWX to fail).  A 1/2 inch bonding strap will also need to be installed from the TWX670 Processor to the negative terminal of the aircraft battery.  Hope this helps."