Hello. I'm a bit confused on this subject. I looking at the gtn650 for kln89b replacement. "If" I wanted to push that gps display, onto any old efis,(lesser espensive experiemental type efis) is it still then considered certified? I thought I had read somewhere, that be the case. I may only afford just to update the gps at this point, but wanted my options, as to what to add if I were going to take it up another level. I currently use a TT a/p and that control head would need upgrading, to coincide with the 650. (not the servo's however) So whatever efis I may get, must keep within the boundaries of being certified, and work with the trutrak. Thx for any advice. DM