There are only 2 differences that set the Harley Davidson drivetrain apart from the Lightning. First, and most importantly, the Harley truck features a larger upper blower pulley which accounts for about a 2 psi LOSS in boost against the stock Lightning level. Secondly, the computer is programmed with a richer, and therefore "safer" air/fuel ratio and tune due to the utility nature of the Harley truck. Ford knows that most Harley owners are much more likely to haul loads or tow with these vehicles, so they tuned the computer with a safer air/fuel ratio than that of the lean 13:1 that the Lightning comes with. This really doesn't have much effect on horsepower, it is just mostly for safety, as the boost is the main performance difference. C&L "Stage 2" package consists of our complete 95mm mass airflow and filter assembly with all necessary mounting hardware and a dyno developed tune which is preloaded into our Predator Tuner. This kit is guaranteed to add an average of 25-30 rear wheel horsepower, which is enough to slightly surpass the rear wheel output of a stock Lightning.