DG Performance 03-4150 - O-Series Slip-On Exhaust ( Aluminum) for Yamaha Raptor 660R (2001-2005 ) DG O-Series - the value is phenominal! As tested by Dirt Bike Magazine! Recieves 9 Out Of 10! Aluminum body and Stainless steel midsection Repackable muffler Approx. 5.5 pounds Quality is excellent. The quality compares well to almost anything this side of a $600 complete system - Dirt Bike Magazine