Jones Exhaust Flowpack Muffler JFP300 3.00 Inch Inlet / Outlet Jones Flowpack’s are a 16 gauge aluminized steel, baffled muffler. They are 5” round, with a 13” shell length and 19.5” overall. Like the Jones Full Boar mufflers, they are designed with the Flow Deflector Technology which allows for maximum flow and power gains. They produce a sound that is powerful and aggressive.