BMW Performance Exhaust Active Autowerke BMW Performance Exhaust Collection Active Autowerke has spent the better part of three decades researching, developing, and tuning our BMW performance exhaust products. All of our BMW headers, downpipes, rear sections, mufflers, and test pipes are manufactured from high-quality stainless steel and carry a limited warranty. For the ultimate in power, sound, and quality turn to Active Autowerke's BMW exhaust collection! http://store.activeautowerke.com/collections/exhaust