BD Diesel Exhaust Manifold Kit - Ford 2015-2019 F250 6.7L PowerStrokeBD focused on solving one of the Ford 6. 7L common failures, the exhaust manifolds. Crafted with a heavy duty 0. 275" thick walled Hi Silicon ductile casting, this makes these manifolds 75% thicker to combat cracking due to high exhaust temperatures. Thermal durability has been improved with longer exhaust studs and spacers plus thicker, more durable machined bolting flanges. To maximize exhaust flow, computational fluid dynamics were used to optimize