I have FSX. I'm confused as to why there are two GTN products. If the GTN750 product contains the 650 touch why is the 650 sold separately? Is it so the 650 can be used independent of the 750 for whatever reason? One reason I ask is that I don't want to buy the 750 and miss on the discount for both if I MUST have both for my install. I'm installing in the Carenando Phenom 300. Why would I need to purchase both gauges? Thanks for the help!