The X-pipe forward mid section bolts right-up to the header collectors. The placement of the O2 sensor bungs makes screwing-in and reconnecting the sensors a cinch. Notice the X-type cross-over is now at the front of the mid-pipe. Not visible are the 49-state legal, severe-duty cats located where the stock crossover pipe was. The ARH collectors and remaining balance of the exhaust system is made of the same 304 stainless steel with a tube thickness of .065-inch.