 The top of the line was the Stage 3 Mustang, but Roush recognized that many buyers did not want all the features (particularly cosmetic) that the Stage 3 offered, so beginning in 2007, Roush introduced the 427R.The 427R featured the same suspension, power-train, and most of the body-kit of the Stage 3, but it lacked the rear fascia and rectangular exhaust tips of the various Stage models.It produced an additional 20 hp (14.91 kW) and of torque over the Stage 3 Mustang, due to an upgraded ECM (electronic control module).