Typically the stock panhard bar is more than sufficient for strength. However if you lower the car you need an adjustable panhard bar to center the rear axle. But when the rear end of your car drops during acceleration your axle will shift to one side. I think it is the passenger side it shifts toward.
If you want an upgrade over the panhard bar then you install a Watts Link as it will maintain the axle centered under the car at all times if adjusted properly.
2013 GT, Track Pack
, Recaros, Kooks Axlebacks, Airaid CAI, BMR Rear Adj. LCAs, BMR Relocation Brackets
, JLT Oil Separator(s), Barton 2 Post Shifter Bracket
, Steeda Motor Mounts
, Barton Shifter
, JHR Clutch line, BMR adj. UCA and Mount, Kooks 1 3/4 headers/catted H, DSS Al Shaft
, BMR Loop
, Vogtland Sport Springs front/BMR rear, Strange Adj. Struts/Shocks, Extended ball joints, Steeda Bumpsteer Kit, Whiteline Tranny Mount Bushing, Borla Overaxles, BMR Watts, Vorshlag 3" Ducts