HMF Kawasaki KFX 700 2004 - 2010 Brushed/Polished Dual Full Exhaust Muffler + JET + KN The Performance Series uses a 2 1/8" non-restrictive core for maximum flow. Depending on the model, you can expect a 4-6 dB increase over stock. The exhaust shell is made of T6061 Aluminum that weighs substantially less than stock. USFS Approved: All HMF off road exhausts come with a USFS approved spark arrester. Included: Individual Keihin Round Jets: 142, 145, 148, 152