Nearly everybody thinks you need a GI-106A indicator with the Garmin 400 and 500 series, but the manual has a pretty good list of alternate GS indicators that also work with their units. King KI-109 and KI-525 indicators are pretty dang cheap on the used market, shaving another $1000 - $1500 off the cost of making a 150/152 fully IFR capable. Where I live in Arizona is either severe VFR or don't dare fly IFR monsoon season thunderstorms, but SoCal often has a marine layer for IFR or marginal VFR. Since I need to go into and out of Hawthorne and Santa Monica, I'm putting 400Ws into all of my aircraft. With a total equipment cost of less than $3500, why wouldn't I?
