I'm sure I saw that GSX does change some files in FSX. One that I can think of is the pushback cart. I don't recall it changing my fsx.cfg though. I also find that it doesn't have that much of a hit on my frame rates, which I'm surprised about when you consider all those things that suddenly appear when you press CTRL+F12 and calling for deboarding, which to bring the into the scene. I was getting 24 -26 FPS with the CS707-300 at the default YMML airport both before AND after bring the GSX items into the scene. About every five seconds, it would drop to about 14 FPS but immediately return to 24-26 FPS (only stays on 14 FPS for about one second).

Oh and it must change the fsx.cfg because GSX must be added to your list of "trusted" gauges. Not sure of anything more than that. But as CoolP says, you can backup the fsx.cfg before installing it. ;)

Mark