Ford Shelby GT500 Track Testing - Shelby Bolt On Bonanza

While we were making changes to the car after each run, we placed two fans on the Shelby to cool it down. We kept the engine temperatures the same on each run, and made sure the blower was cooled down before we took another stab at the Raceway Park quarter-mile.

Running Free

With drag radials helping us effectively get the power to the pavement and a custom tune that resulted in some hidden power, the time to free up the breathing of the Shelby was upon us. After the last pass with the new tune, Shaun Lacko of JDM jacked up the rear of the Shelby in preparation for the trackside exhaust install we had scheduled. Not everyone will go for headers and a cat-free exhaust, so we wanted to see what a simple after-cat exhaust would do. Allowing for sufficient cool-down before he wriggled his way under the specialty S197, Lacko replaced the stock exhaust with a MagnaFlow after-cat system.

The stock exhaust on the Shelby is, for a production car, pretty good in its own right. Featuring cast-iron exhaust manifolds and 2.5-inch-diameter pipes, the heart and soul of the system is the factory-installed x pipe system. While the stock exhaust is good, we were of the impression that it was still a bit restrictive. Enter the MagnaFlow piece.

The MagnaFlow system is a complete system that comes with mufflers, piping, and all neces-sary hardware. Made of stainless steel, the sys-tem is mandrel bent and comes with a pair of good-looking polished stainless steel tips. Even though the tubing diameter is the same as the stock system-2.5 inches-we expected an improvement due to the fact that the mufflers and tubing on the MagnaFlow system offered less restriction than the stock pieces. And, we'd be doing it right at the track, with basic hand tools, proving that anyone can do the swap in his or her own driveway. Only a few dragstrip passes would truly tell the tale, though, so once Lacko had everything buttoned up, we dropped the jack and then the clutch for three more runs.

By the end of the day, we were able to drop a stock Shelby GT500's e.t. by a little less than 6-tenths of a second while picking up almost 2 mph with three simple bolt-ons. With the beast awake, it's now time to let it wreak havoc. Can you say boost and gears?

When the Shelby flew through the finish line on the first pass with the exhaust, we were impressed with the result. After traveling 60 feet in 1.78 seconds-our best short time thus far-the Shelby ran an 11.831 at 117.03 mph. Backing that run up was another 11.8-second run, an 11.897 at 117.25. Just to be sure, we rode the steed one more time with the exhaust, running an even quicker 11.785 at 117.31. On that run, we recorded a 1.777 60-foot time.

With the air getting worse as the day progressed, the Shelby continued to pick up sizeable gains in performance. The exhaust dropped our elapsed times another tenth and a half, and we picked up almost a full tick on the speedometer. Obviously, the MagnaFlow after-cat system allowed the big mod motor to breathe easier. In addition, the exhaust seemed to add some low-speed torque to the Stang, as the 60-foot times improved by 5-hundredths of a second with no changes to launch rpm or procedure.

The Finish Line

We drove to the dragstrip in a bone-stock Shelby GT500 carrying hand tools, drag radials, a laptop and flash tuner, and an after-cat exhaust system. Six hours and several sets of dirty hands later, we turned the brutally fast SVT special into a 'Vette killer with a few basic bolt-ons. On the surface, these three bolt-ons (stickier tires, a tune, and an exhaust system) are something an everyday Mustang owner does to his or her car. In the case of the Shelby, these three modifica-tions turned the car into something that will pulverize anything it lines up against at the track. Starting off in the low- to mid-12-second zone, we ended up powershifting our way to an 11.78-second best, while improving trap speed from 115 mph to 117. If you break out the calculators and do the math, we dropped 0.595 second off of the Shelby's original elapsed time (0.730 second off of the back-to-back 12.5-second runs) while picking up nearly 2 mph. Not too bad for a day's work.