On the Dyno
Going into this project, we knew that adding long-tube headers and 3-inch exhaust pipes would promote a nice torque gain for Sean's already torquey '08 Shelby GT500. However, the big surprise was the increased horsepower we saw with the addition of Kooks' long tubes, and a little SCT tuning that was handled by our friend Lance Keck.
It's important to note that while the peak-power number achieved with the headers does look insane, it is derived using a baseline peak of 604.82/538.16. The lower numbers reflects the true, SAE, on-the-ground horsepower and torque (according to a Dynojet chassis dyno) that the GT500 had on tap as Sean drove it around with the bone-stock exhaust.
However, the bottom line is that the Kooks exhaust system and sharp tuning made an impressive performance gain on Sean's mega-blown Shelby, and it opens the door for easily going straight to the engine's threshold, with the addition of higher-octane fuel and tuning.