aFe Twisted Steel Down-Pipe Catted 13-16 Cadillac ATS L4-2.0L (t)aFe Twisted Steel Down Pipe Catted 13 16 Cadillac ATS L4 2. 0L (t) 100% TIG Welded by certified craftsmen for race proven strength and durability. TIG Welding provides the strongest welds reducing stress cracks. Paired opposite firing cylinders with equal, specifically tuned primary lengths maximizes scavenging and increases torque throughout the powerband. High grade stainless tubing with a uniform brushed finish provides a beautiful look and high