Borla Big Block Chevrolet 396/402/427 2.5in Offset Inlet / 2.5in Center Outlet Crate MufflerBorla Big Block Chevrolet 396 402 427 2. 5in Offset Inlet 2. 5in Center Outlet Crate Muffler Borla's CrateMuffler is the world's first muffler purpose built to optimize the sound & power of crate and custom built motors. The mufflers are directional. The outlet can be identified by the mounting bracket welded to the endcap. The directional design provides custom sound, tuned for each engine family and will dramatically reduce, or eliminate drone on