These aFe Atlas XP Y - pipes feature a true 2 Into 1 mitered merge collector that eliminates dead space that can cause turbulence and hinder the flow that formed collectors are prone to produce. They are manufactured from aluminized steel, feature mandrel - bent piping, and high - quality OEM - style flanges with band clamps are used for a bolt - on, leak - free installation. The Y - pipes are available with high - flow 300 cell catalytic converters for better flow without CEL lights, or without catalytic converters for true race performance.