Thus, changes to the 5.0-liter V-8 were not just to increase its output but also to alter its nature. Not surprisingly, the modifications are extensive. There's a new intake manifold and ported cylinder heads for better breathing. An engine oil cooler, a lighter-weight valvetrain, forged (rather than cast) aluminum pistons, and forged connecting rods are designed to handle higher engine speeds. Ford engineers used the Boss 302R racing car as a development test bed, and, based on their experience at the track, they revised the road car's radiator to improve engine cooling and added baffles to the oil pan to prevent oil starvation. The net result of all these changes is an engine redline that has been raised by 500 rpm to 7500 rpm and an increase in power output from 412 hp to 440 hp at 7500 rpm-at a cost of 10 lb-ft of peak torque, with the Boss 302's V-8 rated at 380 lb-ft at 4500 rpm.
One of the more interesting aspects of the Boss engine is its exhaust system. Supplementing the standard Mustang GT's dual exhausts are two additional pipes that exit just ahead of the rear wheels. These side exhaust outlets incorporate metal discs that keep the sound at legal levels-but they are removable, should the owner want something louder. The Boss is plenty vocal even with the discs in place, as the induction sound tube has been retuned and eleven pounds of sound deadening have been stripped out.
The engine sends power rearward via an upgraded clutch with a steel-backed disc and a short-throw, close-ratio six-speed manual (no automatic is available). Whereas the Mustang GT has a 3.31:1 final-drive ratio, the Boss gets a 3.73:1 unit, with carbon-fiber friction plates in its limited slip; a Torsen rear axle is standard on the Laguna Seca model and is optional (bundled with Recaro seats) on the regular Boss 302.
Any car expecting to see racetrack duty needs serious brakes, and so the Boss upgrades from the Mustang GT's 13.2-inch front discs to the GT500's fourteen-inch vented front discs and four-piston Brembo calipers. The GT's standard 11.8-inch rear rotors are retained, but the pad material is upgraded. Brake lines have been stiffened to improve pedal feel. The Laguna Seca additionally receives front brake-cooling ducts-they're available as an accessory for the standard Boss 302.
As expected, the Boss features firmer springs, antiroll bars, and suspension bushings, but the car takes the driver-tunable racing aspect one step further with manually adjustable front and rear dampers. The fronts are accessible from under the hood and the rears from in the trunk; drivers can use a screwdriver to select one of five stiffness settings. Position 1 is equivalent to a GT with the Brembo brake package, while positions 2 through 5 are progressively stiffer. The Laguna Seca's softest setting (1) matches the Boss 302's firmest setting (5). The steering effort is also driver-adjustable. Electric power steering was introduced with the 2011 model year, and as in the Mustang GT, drivers can choose among three effort levels. Similarly, the traction and stability control systems include a competition mode that allows greater drift angles, or they can be shut off entirely.