We tested the new 2015/16 Mustang GT when it was stock, and while it's certainly the best Mustang yet by a wide margin, we did find room for improvement in certain areas an enthusiast might find helpful, mainly the suspension damping, clutch feel, and exhaust sound. This 2015 Mustang GT has the "full bolt on" treatment, including common consumer-level upgrades to the suspension, engine, shifter, clutch, and exhaust, and it's no surprise that a little fine tuning goes a very long way in a Mustang.