Shorty headers have been installed on SRTs since 2008. Look at this model of a 6.1 engine. They deliver more power horsepower and torque from idle to the mid-RPM range than long tube headers. This makes them perfect for street use. Long tube after market headers, however, do the best job building horsepower and torque from mid-to-high RPMs. They are great if you plan to track your car. Here is the physics behind this. Long tubes create a deep pressure depression that pulls very hard on the intake during overlap. This gets the speed of the incoming mixture up well before it would be if it just depended on piston movement. This enhances the ramming of mixture into the cylinder. Shorties also do a good job of emptying the cylinder of exhaust but don't offer much ram effect because they don't generate very strong negative pressure waves.
