Drew Phillips
October 1, 2009
The stickers may be flashy, but the wheels and tires are all business. Up front, the APR Mustang rides on 285/30-20 Toyo Proxes T1R tires, and massive 15-inch Stoptech brakes are clamped by six-piston calipers.

Check out exclusive photos of the widebody GT-R here.

APR Performance, based in Walnut, California, has been at the forefront of developing performance-oriented body components for the automotive industry for the last decade. Whether for competition at the race track or for the ultimate street car, APR's main focus is always on performance. "All of our products are developed and driven by racers," says KC Chou, owner of APR Performance. "Every one of our products is tested and proven to increase performance on the vehicle." Much of their work has been reserved for imports, like the development of an aerodynamic widebody kit for Subaru's SCCA GT class racecar, but recently they have turned their attention to American muscle and developed a package for '05-'09 Ford Mustang owners. "We chose to enter the Mustang market due to a high volume requests made by owners and track racers," KC tells us. "Many of these Mustangs had high horsepower but lacked traction due to the limited tire widths that could fit within the fenders of the stock-bodied Mustangs."

The idea to build the Mustang you see here, on which the body kit was developed, started in March of 2008. A few hand-sketched designs eventually turned into a 2-D color rendering on AutoCAD that formed the platform on which APR's engineers would work.

The next step was to physically make all of the components on top of a real Mustang, and a team of three designers spent approximately 1,400 man hours forming all of the prototype body panels for the molds. Nine separate pieces were needed to complete the body kit, including the carbon-fiber front splitter, front bumper, front fenders, side skirts, rear fenders, and a rear bumper.

Bare carbon-fiber can be seen by way of the unpainted stripes on the hood, as well as on the rear wing and diffuser, front spoiler, and side mirrors. The rest of the car is painted in a custom BASF red.

Optional carbon-fiber components include a vented hood, a GTC-500 adjustable rear wing, a rear diffuser, and a sideview mirrors. The additional width, 45mm at each of the front fenders and 50mm at each of the rear fenders, gives the Mustang a much more aggressive and hunkered down appearance, especially from the front and rear.

While APR waited to get the production pieces, the Mustang was sent over to SP Engineering in City of Industry, California, for work on the engine, suspension, and interior. To boost the stock horsepower to racecar levels, the company turned to Turbonetics for its single turbocharger system to provide the necessary boost in performance. The kit utilizes a T4 60-1 ball bearing turbo, Spearco intercooler, Raptor blow-off valve, and an Evolution wastegate along with polished stainless steel exhaust tubing and silicone hoses. A high-flow radiator and oil-cooler kit from Mitshimoto mitigate increased temperatures caused by the heat from the turbocharger, and a Magnaflow Magnapack system with TRU X-shape crossover ensures that exhaust gases exit as efficiently as possible.

The rear diffuser is one of many optional carbon-fiber components from APR, which includes a vented hood, a GTC-500 adjustable rear wing, and the sideview mirrors.

After custom tuning using an SCT XCalibrator 2, the result was 435 hp and 460 lb-ft torque at the rear wheels at 8.5 pounds of boost. The five-speed Tremec transmission remains in place, although an ACT six-pad race clutch and lightweight flywheel help transmit the additional power.

In the handling department, the Mustang was set up with a Variant 3 coilover system from KW Suspensions, as well as their front and rear antisway bars. Massive Stoptech 15-inch rotors with six-piston calipers provide excellent braking power up front, helped by stainless steel brake lines, upgraded pads, and stock size drilled rotors at the rear, all also from Stoptech.

Taking advantage of the extra width of the widebody kit, SP Engineering fitted the widest set of rear tires we've ever seen on a road-going S197 Mustang-a set of 345/25-20 Toyo Proxes T1R tires on 20x12.5-inch Work VS-XF wheels complemented by 285/30-20 units on 20x9.5-inch wheels up front. This was done purposefully by APR, which designed the body kit to accommodate this size of tire. "The wider tires allowed for higher levels of grip, and keeping the tires within the fenders allowed for reduced aerodynamic drag compared to a stock-bodied Mustang," says KC.