do some research, all the professional builders say sub frame connectors are not needed. Griggs builds some of the hottest mustang track cars and they do not use them. I too can attest to jacking a corner of the car and seeing no twist or flex at all.
"Also, I spun out during a ice storm last year and I can tell a difference in how my car corners, and the tires show uneven ware like there is a problem with the frame IMO."
not sure what you are implying here? do you think you twisted your frame? If so connectors wont fix the problem, you need the frame straightened/repaired. Installing them on a twisted frame will only make it worse.
"Consumer Reports for my 2006 GT says that it has exterior stability problems."
exterior stability problems can be caused by many different things, chassis flex would be seen on racing and hi HP/Torque applications, not the normal street situations that consumer reports would be testing for. Bolt on sub frame connectors on a 2011 would only add weight and the holes drilled will weaken the structure and give oxidation a place to begin.
"Never hurts to have extra security since my wife and I are trying for a little one"
what security would sub frame conn give you?
have a good shop check for frame damage if you are concerned your car is unsafe. If you want the connectors for the cool factor, go for it.
UMI DbleAdjLCAs/UMIloweringbracket/UMI DbleAdjPanhard/GriggsRearTorqueTube(eliminatesUpperControlArm)
JLT CAI/JohnLund 93Tune/Baer6PistonCalipers/14"slottedCrossdrilled2piece rotors
BlackChromeFR500s Nitto295rear 275front
CarbonFiber interior Bartonshortthrow/bracket