Quick answer

Install the AT2 stainless slip-on by first removing the stock muffler, then test-fitting the new muffler and mid-pipe before tightening any clamps or springs. Work slowly, check clearance around the swingarm and passenger peg, and finish with a sound check at idle and low rpm.

Why the AT2 is a smart first upgrade for the Z900

The AT2 slip-on drops weight compared to the stock muffler and gives the 948cc inline-four a sharper exhaust note. It is a straightforward bolt-on for most home mechanics, but the install still rewards patience: rushing the removal or skipping a test fit can lead to rattles, misaligned springs, or contact with the bodywork.

What you need before you start

Gather basic hand tools, a torque wrench, and a clean work area. The AT2 kit includes the muffler and mid-pipe, but you will reuse the stock mounting hardware unless otherwise noted. Have a soft mallet and penetrating oil on hand for stubborn stock clamps. A second person helps when aligning the muffler to the mid-pipe.

Step-by-step AT2 slip-on installation

  1. Remove the stock muffler: Loosen the clamp bolt at the mid-pipe joint, then carefully slide the stock muffler off its mounting bracket. Support the muffler as you remove it to avoid stressing the header. Common mistake: yanking the muffler before the clamp is fully loose, which can bend the mid-pipe flange. Check the stock gasket for damage; replace it if it is crushed or missing.
  2. Test-fit the AT2 mid-pipe and muffler: Slide the AT2 mid-pipe onto the header outlet and loosely mount the muffler to the frame bracket. Do not tighten anything yet. Check clearance around the swingarm, rear brake line, and passenger peg. Common mistake: tightening the muffler bracket first, which can pull the mid-pipe out of alignment. The mid-pipe should slip on without force; if it binds, check that the stock gasket is fully seated.
  3. Install the exhaust springs: Hook the supplied springs between the mid-pipe and muffler using a spring puller. Wear gloves and eye protection. Common mistake: stretching a spring with pliers, which can deform the coils and weaken tension. After installing, tug each spring gently to confirm it is seated in both hooks.
  4. Torque the clamps and bracket bolts: With everything aligned, tighten the muffler bracket bolts and the mid-pipe clamp to the specifications in the AT2 instructions. Use a torque wrench. Common mistake: over-tightening the clamp, which can crush the mid-pipe or distort the gasket. Recheck clearance after tightening; if the muffler touches the swingarm, loosen and realign.
  5. Sound check and final inspection: Start the engine and let it idle for a minute. Listen for exhaust leaks at the mid-pipe joint and check that the muffler does not rattle against the frame. Rev the engine lightly to confirm smooth response. Common mistake: skipping the sound check and discovering a leak on the road. If you hear a ticking noise at idle, recheck the mid-pipe clamp and gasket seating.

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