Guys use the stock Subaru manifold to achieve huge horse-power; why do I need the Forsa Manifold?
It comes down to the potential of the entire system. Yes, you can make some excellent horse-power gains with the stock manifold but how hard is that system working? To overcome the restrictions in the stock manifold, all the other components have to work harder. This can result in lower efficiency and more heat. Why make it tough on the system ?, Remove the restrictions and let the system do what it was supposed to do.
