Gains are about 48 horsepower at the crank, impressive. Yes, the manifold comes with software which allows the higher redline. As shown in the horsepower and torque graph below, the difference is night and day in power and torque as well as rpm.
This is a direct bolt on kit including all hardware necessary along with the software. It is priced at a very reasonable $1499 for the manifold, software, and associated hardware. Well worth it to completely transform the car. Check out the video below of a car with the stock manifold and the Integrated Engineering manifold with software set to rev to 7800 rpm.
2008 VW Rabbit 2.5L 5 speed stock rev limit.
2008 VW Rabbit 2.5L 5 speed
IE stage 1 manifold software 7800RPM rev limit.
IE intake manifold