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The JLT setup is sano. The...
The JLT setup is sano. The carbon-fiber intake tube looks great and the system is clearly designed to ensure direct, smooth airflow into the throttle body.
DiabloSport Predator
With all the changes we've made to our project Shelby, there's no doubt the air/fuel mixture is now much leaner than it was when the car was in stock trim. We're using DiabloSport's Predator unit for Shelby GT500s (PN U7145; $369.99) to make things right with the PCM's calibration and ensure that Carlos' ride runs smoothly, and warning lights aren't triggered. The Predator contains a series of GT500-specific tunes that modify spark and fuel functions associated with the type of bolt-on upgrades that are made.
Saul selected Predator's JLT cold-air intake/2.7-inch pulley (with 93-octane fuel). With the exception of our project being limited to 91-octane gas, the tune proved to be just about spot-on. It only required a small amount of fine adjustment, which Saul was able to adjust directly with the Predator. Since we're using the dyno to measure performance, a wideband O2 sensor helped us determine the correct amount of fuel to add to the tune, which ended up being a total of 5 percent from 2,000-7,000 wide-open throttle, bringing air/fuel down to a more-than-safe 11.0 across the rpm range. Had we added a complete, 3-inch exhaust system on Carlos' car, a more detailed dyno tune using DiabloSport's Chipmaster Revolution tuning software would be necessary.
Carlos' Shelby gave us quite a surprise during our initial test for baseline horsepower and torque data. Based on the performance of other stock Shelbys that we've tested on Extreme Automotive's Dynapack Evolution 4000 chassis dyno, we expected to see peak horsepower in the neighborhood of 442-446 at the rear wheels. Our test subject fell way short of that benchmark, recording a somewhat-disappointing 426.41 peak rear-wheel horsepower and 372.08 lb-ft of torque.
Call it a "wall of silence,"...
Call it a "wall of silence," if you will. This blockage inside a Shelby's stock mufflers is not only detrimental to how the car sounds, it also hinders performance in a big way.
The jury is still out on why the numbers were so much lower, but one variable that may have had some influence in the car's performance (before and after the upgrades) is the ambient temperature inside the dyno cell. Unfortunately, we can't always perform dyno tests or other critical evaluations during "perfect" weather conditions. With a June heat wave gripping the San Fernando Valley and highs reaching upward of 111 degrees in Canoga Park, where Extreme is located, our Shelby project was done in 107-degree heat. So hot weather might have had something to do with it. However, we're not saying that ambient temp alone sapped approximately 20 hp from Carlos' car in stock trim, and we're not saying the car had some sort of mechanical or drivetrain problem. The bottom line is that the dyno doesn't lie, and it is what it is.
In that vein, the parts we put on Carlos' GT500 definitely are what they are-power producers. In just over half a day, we bolted on (and plugged in) a total of five simple performance parts that added more than 127 peak horses at the back tires at 6,000 rpm.-an incredible gain considering the relatively low cost for everything, and the money saved on labor if you install the parts yourself.
 Friction generated when removing...  Friction generated when removing (and installing) supercharger pulleys creates a lot of heat in the threads of the puller tool. A modest coating of antiseize helps eliminate galling and/or literally welding pieces of the tool together. |  Steeda's Ford/Eaton supercharger...  Steeda's Ford/Eaton supercharger pulley puller (PN 555-8902; $149.95) is mandatory for removing a GT500's stock wheel. Saul uses a 11/8-inch socket and turns the carrier bolt clockwise to extract the stock wheel. It's important that the engine and blower are cool before trying to remove or install a pulley. |  We're using Steeda's 2.7-inch...  We're using Steeda's 2.7-inch Shelby GT500 supercharger pulley for this part of the upgrade. The billet-steel pulley directly replaces the factory wheel and should increase boost by about 2-3 psi. Using the Steeda tool to install the new pulley involves the tool's installation bolt, jam nut, a bearing, and a 9/16-inch flat washer. While holding the installation bolt with a 1-inch box-end wrench, turn the jam nut to press the new pulley in place. The flat washer ensures the pulley doesn't run beyond the end of the supercharger's shaft. |
 With the rear of the car properly...  With the rear of the car properly elevated, Saul removes the restrictive stock mufflers. |  Installing the Bassani exhaust...  Installing the Bassani exhaust system is as easy as removing the factory pieces. The mufflers' inlet tubes are completely mandrel-bent and mate perfectly with a Shelby GT500's stock catalytic tubing. The cans themselves are of highly polished stainless steel construction, with embossed 3-inch tips. Everything fits in the factory location using the OEM brackets for the hangers and clamps (a 15mm wrench is required) provided with the kit. |  Bassani's mufflers are a straight-shot...  Bassani's mufflers are a straight-shot design. There are no internal restrictions, so Shelbys benefit quite a bit in the areas of torque and sound (deeper, more muscular sound at idle than stock cans). The mufflers don't overwhelm the whine of the blower when load is applied, which is pretty cool. |
 DiabloSport's Predator hand-held...  DiabloSport's Predator hand-held tuning device is easy enough for novices to understand and use. When used by professional tuners, the unit functions as a conduit between the computer developing the custom fuel and timing parameters and the vehicle's PCM. |  This ready-made tune in the...  This ready-made tune in the Predator unit is a good match for our selected mods. After downloading the program into the Shelby's PCM, the new calibration only required a small amount of tweaking before it was perfect. |  We suggest adding a bung just...  We suggest adding a bung just in front of the catalytic converter and using a dyno or an aftermarket wide-band O2 sensor/gauge to monitor air/fuel levels when your 'Stang is being dyno tested or tuned in any way. |