A quality aftermarket panhard bar does wonders to minimize lateral movement of the rearend, the only complaint I had of the car. As far as road noise, I found my 2011 premium extremely quiet on the highway, as quiet as my sisters Lexus ES. There are many trim levels of the Mustang, drive different ones to find the one you like.
2011 GT Coupe Premium, Black exterior with Charcoal black turned leather interior. Rapid spec 400A with 6-speed MT, 3.73 limited slip axle, 19" painted aluminum wheels, HID headlamps, comfort package. FRPP tune with K&N air filter. FRPP Touring axle back exhaust with Borla 2 3/4" over axle pipes. ST Suspensions coilovers w/GT500 mounts. Spohn poly/del sphere adjustable lower control arms and Spohn adjustable panhard bar with Steeda panhard bar brace. Hotchkis Sport sway bars.