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S4 Cat-back exhaust

Why do it

Tools you'll need

• Jack and 4 jack stands
• Socket set
• Torque wrench
• Penetrating oil
• Jack and 4 jack stands
• Socket set
• Torque wrench
• Penetrating oil
• Jack and 4 jack stands
• Socket set
• Torque wrench
• Penetrating oil
• Jack and 4 jack stands
• Socket set
• Torque wrench
• Penetrating oil

Starting out? See our budget tool list.

Parts to buy

• Techtonics stainless cat-back 252-590 (2000-2002) For the B5 S4 2.7T.Fits 2000–2002 · 2.7T
• Milltek cat-back SSXAU872 (2004-2005 4.2L) For the B6 S4.Fits 2004–2005 · 4.2L V8
• AWE Touring Edition 3010-42018 (2010-2016) For the B8 and B8.5 S4. The same exhaust as our video.Fits 2010–2016 · 3.0T supercharged
• AWE cat-back 3010-42054 (2018-2025) For the B9 and B9.5 S4. The same brand as our video.Fits 2018–2025 · 3.0t

Double-check fitment before buying. We may earn a commission when you buy through these links, at no extra cost to you.

Steps

1. Prepare

   • Raise the car and soak the bolts.
   ▶ Watch this step (on a B5 S4) (2:21–3:25)

2. Remove the old exhaust

   • Undo the bolts and slide it off its hangers.
   ▶ Watch this step (3:25–4:37)

3. Install the new system

   • Hang the pipes and bolt them up.
   ▶ Watch this step (4:37–5:51)

4. Finish up

   • Line it up and tighten everything.
   ▶ Watch this step (7:52–9:10)

5. Remove the stock exhaust

   • Undo the clamps and slide it off its hangers.
   ▶ Watch this step (on a B6 S4) (0:47–2:23)

6. Install the new exhaust

   • Hang the pipes and tighten the clamps.
   ▶ Watch this step (3:19–7:56)

7. Remove the stock exhaust

   • Undo the clamps and slide it off its hangers.
   ▶ Watch this step (AWE on a 2010 S4) (0:54–2:56)

8. Install the new exhaust

   • Hang the pipes and tighten the clamps.
   ▶ Watch this step (2:56–5:31)

9. Final adjustments

   • Line up the tips.
   ▶ Watch this step (5:31–5:54)

10. Remove the factory exhaust

    • Undo the clamps and slide it off its hangers.
    ▶ Watch this step (AWE on a B9 S4) (1:43–6:25)

11. Work past the tight spots

    • Watch how to get around the tight parts.
    ▶ Watch this step (6:25–8:39)

12. Install the new system

    • Hang the pipes and clamp them up.
    ▶ Watch this step (8:39–11:23)

13. Final adjustments

    • Line up the tips and tighten everything.
    ▶ Watch this step (11:23–13:12)

How to know it worked

• No exhaust leaks at the joints.
• Tips sit even in the bumper.
• Nothing touches the body.
• No exhaust leaks at the joints.
• Tips sit even in the bumper.
• Nothing touches the body.
• No exhaust leaks at the joints.
• Tips sit even in the bumper.
• Nothing touches the body.
• No exhaust leaks at the joints.
• Tips sit even in the bumper.
• Nothing touches the body.

Follow your part's instructions and your service manual's torque specs.