Frank H. Cicerale
December 1, 2008

The SLP 600HP Performance Pac for the Shelby GT500 is a surefire and easy way to add some venom to the snake's bite.

Of course, a true MM&FF evaluation wouldn't be complete with out a thorough dragstrip flogging. The GT500, which was equipped with the Powerflow exhaust system with the 4-inch tips, was driven to Old Bridge Township Raceway Park in Englishtown, New Jersey, our resident test facility. We promptly opened the hood, and while a pair of portable fans were blowing air onto the blower to cool it down, we jacked the rear end up and swapped the stock rear sneakers for a pair of 26x11.5-inch Mickey Thompson tires mounted to 17-inch Mustang GT rims. This was done due to the fact that the added power and torque would make it difficult at best to get the beast to hook upon launch.

Since this car wasn't tested in bone-stock trim, we had to look back into the MM&FF archives, where we found a best elapsed time of 12.38 seconds at 115 mph for a stock GT500. After perfecting his launch and shifting techniques, MM&FF's own Evan Smith promptly ripped off an 11.43 at 122 mph. This was with a 1.72 best 60-foot time, and on the same day MM&FF tested the new GT500KR. We have to say, the SLP-prepped GT500 held its own against the new Ford super Stang. Not too bad for some added bolt-on parts.

To install the new headers, you will have to remove the steering column intermediate shaft and move it out of the way. This will allow you to sneak the headers in with a minimal amount of knuckle scraping, tool throwing, and cursing.

In addition to ripping it up at the dragstrip, we also took the car for a weekend to evaluate its road manners. After all, with the added horsepower, we wanted to see how tractable the car was when performing street duty. After putting on a fair amount of miles over the course of a few days, the verdict was one of happiness and, as expected, success. There was no surging when it came to the revised tune, and even though the fuel trims were changed, fuel mileage was still respectable, as we knocked down 24 mpg on the highway during one stretch. Over the course of three tanks of 93-octane pump gas, the Shelby averaged 18.5 mpg both on the highway and on roads around town. The exhaust tone emitted by the long-tube headers, x-pipe system, and exhaust system was not overly abrasive, though there was a drone at 80 mph that made us have to crank up the stereo just a bit to overcome. Overall, though, the sound and added power not only allowed the car to make a statement, but back it up. Just ask the patrons in front of a local eatery who witnessed the Shelby roll up in authority and scare a pesky 350Z into the depths of the parking lot.

The stock airbox and throttle body is also taken out to aid in installation of the headers. While the airbox is out of the car, the stock air filter was replaced with the high-flow piece that comes with the Pac.

All in all, the SLP 600HP Performance Pac for the Shelby GT500 is a surefire and easy way to add some venom to the Snake's bite. The best part of it is the fact that the parts have been tested and approved by SLP, and are all available separately from one another, just in case you don't want the whole shebang. "The advantage to the Performance Pac is that it is thoroughly tested to not only guarantee the horsepower and torque levels advertised, but it is also guaranteed to be safe for the engine for the long haul. By creating a package with components from one supplier, we know exactly how the vehicle will react, and can create a tune that comes with each package so that each package performs the same on every car, every time. This allows the customer to install the package and the tune and hit the road quickly without any worries or need for added dyno time."

While SLP has no plans to add anything to the package as of now, with how well it works and what it does for the Shelby GT500, would you really want any more? I guess by asking that question, it means we're bringing a loaded weapon to a knife fight. Let's get it on!