Stage 3 Roush is 415hp/385tq
Roush 427R = 427hp
Building off the already legendary 427 name, one already used for their high performance 427 cubic inch 351w stroker, Jack Roush and crew unveils their most powerful Ford Mustang to date. Based on the Roush Stage 3 Mustang, the 427R adds an additional 12 horsepower for a total of 427 ground pounding ponies (hence the name).
The additional horsepower comes by way of more agressive tuning and a different exhaust system, with much of 427 horsepower power coming from the new ROUSHcharger system which Roush offers via the official Roush website. The supercharger sits atop the standard 4.6L 3v SOHC engine found in the 2007 Mustang.