Dinan's Free Flow Axle-Back Exhaust for the 540i provides power gains without the excessive noise associated with typical ''performance'' mufflers. The Dinan exhausts feature rigid and durable muffler cases manufactured from 20 gauge 304 stainless steel for optimum corrosion resistance. Internally, the systems feature Dinan's Tuned Resonance Chamber Technology providing the optimum balance between maximum power gains and a civilized, yet sporty exhaust note. The Dinan exhausts also provide substantial weight reduction compared to the stock mufflers. The mufflers weigh in at 18.5 lbs. compared to the stock systems at 34 lbs. Dual 3-inch diameter polished stainless steel exhaust tips give the cars a tasteful performance look as well.