What's one of the most overlooked anti-flowing Subaru pieces you ask?? ...The stock exhaust manifold crossover. 50% of your exhaust gasses are passing through this tiny tiny pipe and that is not good. Well here comes the solution for this problem. Welcome the GrimmSpeed Version 2 Subaru Exhaust Manifold HiFlow Crossover. Well they've decided to step it up a notch with the first revision of the crossover. Meet HiFlow Crossover v2. Immaculate welds, smooth as butter 2" stainless steel, thick 12mm stainless flanges. You can't beat this piece. Customers have seen up to 15 HP INCREASE when combined with a PnP Subaru Exhaust Manifold. This unit is built from 2" 304 Stainless Steel throughout, maximizing exhaust flow from cylinders 1 and 4 to the manifold collector for faster turbo response. This unit has a flex in the center to allow for easier installation and for thermal expansion during hard driving. This includes all the gaskets necessary for installation.