Mongoose Exhausts Mongoose Performance Exhausts are one of the longest established names in the stainless steel exhaust world.All Mongoose exhausts are produced using the best materials and the finest manufacturing processes. The systems are made from 1.5mm or 1.2mm thick T304 stainless tubing bent on the finest mandrel bending machines giving amazing build quality.We are confident that our exhausts will never rust or fail, so much so that each Mongoose is guaranteed for your lifetime.