Arrow 71874PRI Pro-Race Nichrom Slip-On Mufflers w/Steel End Cap for Kawasaki Z 400 19-20/Ninja 400 08-20Arrow Pro Race Slip On Exhaust Kawasaki Ninja 400 At the turn of the 21st century, MotoGP saw a revolution in exhaust design that strayed away from old school round canister shapes and instead incorporated the muffler into the mid pipe itself. This design not only reduces mass but also overall weight. Now this same design is available to you in the form of the Arrow Pro Race Exhaust. From its cone shaped sleeve, angled round end cap, integrated