Before You Begin: Tools, Safety, and Preparation

Installing ECS Tuning upgrades on your B9 S4 is a rewarding project that yields measurable gains in power and handling. However, proper preparation and safety are non-negotiable. Begin by allowing the engine and exhaust system to cool completely if the vehicle was driven recently. A cold drivetrain reduces burns and makes component removal easier.

Essential Tools and Workspace Setup

  • Socket and wrench set – metric sizes from 8mm to 19mm, including extensions and universal joints.
  • Torque wrench – use a beam‑type or click‑type wrench for precise fastener torque. Many ECS hardware kits include specific torque specs.
  • Floor jack and four jack stands – always lift on the factory pinch‑weld jack points and set stands under reinforced frame rails. Never rely on the jack alone.
  • Wheel chocks – place behind the rear wheels if lifting the front, and vice versa.
  • Screwdrivers, trim tools, and pliers – for removing plastic covers, clips, and wiring connectors.
  • Penetrating oil – spray on exhaust bolts and suspension fasteners 30 minutes before work. This minimizes seized‑bolt frustration.
  • Shop rags, gloves, and safety glasses – exhaust systems have sharp edges; suspension springs store energy.

Parts and Supplies

Your ECS Tuning kit arrived with hardware, but you’ll also need fresh gaskets (exhaust, throttle body, or intake manifold gaskets if your upgrade requires them). Keep a few zip‑ties and electrical tape on hand for securing wiring or hoses. For suspension work, a spring compressor is mandatory – never compress coil springs with improvised tools.

If you are upgrading the cold air intake, the stock MAF (mass airflow) sensor will be transferred. Have a small Torx or Phillips driver ready. For exhaust work, buy new exhaust flange gaskets and a tube of anti‑seize compound for bolt threads.

Finally, read the full instruction set that shipped with your ECS Tuning kit before touching the car. The steps below supplement those instructions with real‑world tips specific to the B9 S4 platform.

Upgrade 1: Cold Air Intake System

The B9 S4’s factory airbox is restrictive. An ECS Tuning cold air intake opens the intake path, reduces intake air temperature, and adds a satisfying induction sound. Expect a gain of 8–12 wheel horsepower and improved throttle response after a tune, but even on a stock ECU the intake flow is freer.

Removal Steps

  1. Disconnect the negative battery terminal. This prevents accidental airbag or sensor faults while the system is opened.
  2. Unclip the engine cover by pulling it upward at the rubber grommets.
  3. Remove the factory airbox top. Disconnect the MAF sensor harness by pressing the tab and pulling straight out. Some B9 S4s have a sensor lock – slip a small flathead under the locking tang.
  4. Loosen the hose clamp at the turbo inlet and pull the airbox outlet tube off. Set the factory assembly aside.
  5. Remove the lower airbox housing by unclipping it from its rubber mounts. The mounting points may require a firm upward yank – avoid prying against the radiator or intercooler.

Installation of ECS Tuning Intake

  1. Inspect the ECS filter element. Some kits come pre‑oiled; if yours is dry, oil it lightly with the supplied filter oil. Over‑oiling can contaminate the MAF.
  2. Position the ECS heat shield and secure it with the included hardware to the factory mounting points. The shield’s seal against the hood underside is critical – press it down firmly so it contacts the hood seal.
  3. Transfer the MAF sensor to the new intake tube. Pay attention to the sensor’s orientation arrow (usually facing airflow). Torque the screws snugly – overtightening can crack the sensor housing.
  4. Attach the intake tube to the turbo inlet. Use the supplied silicone coupler and T‑bolt clamps. Tighten the clamp nearest the turbo first, then the one at the filter side. Torque to 4‑5 Nm; overtightening distorts the silicone.
  5. Install the filter onto the tube and tighten the clamp.
  6. Reconnect the MAF harness and verify the wiring does not contact the serpentine belt or fan.
  7. Reinstall the engine cover, reconnect the battery, and start the engine. Let it idle for two minutes to allow the ECU to relearn idle airflow. Check for any unmetered air leaks by spraying soapy water on the couplers – bubbles indicate a leak.

For more detailed intake installation videos, visit the ECS Tuning product page for your specific kit. The B9 S4 platform also has extensive community knowledge on Audizine’s B9 S4 forum.

Upgrade 2: Cat‑Back Exhaust System

ECS Tuning’s cat‑back exhaust systems for the B9 S4 remove the restrictive factory mufflers, reduce back pressure, and sharpen the exhaust note. Gains of 5–10 wheel horsepower are typical, but the real benefit is weight reduction (often 15–20 lb) and a sportier sound under load.

Removal Steps

  1. Lift the rear of the vehicle and secure it on jack stands. Remove the rear wheels if you need extra clearance for the muffler hangers.
  2. Spray penetrating oil onto all exhaust hanger rubber isolators and flange nuts. Let it soak while you arrange your tools.
  3. Disconnect the two downstream O2 sensors if you are removing the downpipes (for a full turbo‑back system). For a typical cat‑back, only the rear section is removed.
  4. Use a 13mm or 15mm socket to unbolt the mid‑pipe from the catalytic converter flanges. The bolts may be tight – use a breaker bar. If they strip, cut them off with a rotary tool; have new hardware on hand.
  5. Unclip the exhaust hangers from the rubber isolators with a pry bar or hanger removal tool. Work from the rear forward, supporting the exhaust weight with a second jack.
  6. Lower the stock exhaust assembly. You may need to pull it out from under the car sideways – protect the bumper and heat shields with shop rags.

    7. Installing the ECS Tuning Cat‑Back

    1. Lay the new system on the floor and assemble the sections. Ensure the clamps and gaskets are oriented correctly – gaskets typically go with the flat side against the flange and the raised bead against the mating pipe.
    2. Lift the exhaust into position, starting at the front. Loosely install all clamps but do not tighten yet. Slip the hanger rods into the rubber isolators.
    3. Align the tips symmetrically in the bumper cutouts. This is the most time‑consuming step; the clamps still loose allows you to rotate and slide each section.
    4. Once the tips are centered and gap is even, tighten the clamps to the torque specified in your kit (usually 25‑30 Nm for band clamps). Use a torque wrench to avoid stripping the clamp flanges.
    5. Reconnect O2 sensors if removed, making sure the wiring is routed away from heat shields and rotating masses.
    6. Lower the car and tighten the rear hanger nuts. Start the engine and listen for leaks at the flanges. A soapy water test works here as well. After a short drive, re‑check clamp tightness – heat cycling can loosen them.

    Exhaust Upgrade Tips

    If your B9 S4 is equipped with the ZF 8‑speed automatic, consider adding an ECS Tuning valve control module to eliminate the factory drone‑reducing flaps. This lets you toggle sound levels from the cabin. For manual transmission cars, the drone is minimal but present at 1800–2200 rpm if the pipes are straight‑through – choose a resonated system if cabin comfort is a priority.

    Upgrade 3: Coilover Suspension (Height and Damping Adjustable)

    The B9 S4 OEM suspension prioritizes ride comfort over cornering flatness. ECS Tuning coilovers allow you to lower the car 0.8‑1.5 inches while adding adjustable compression and rebound damping. The result is less body roll, quicker turn‑in, and a more planted feel through sweeping corners.

    Preparation

    Coilover installation requires lifting the entire vehicle. Support the car on four jack stands – never work under a car supported only by a hydraulic jack. Remove all four wheels. Loosen the top strut nuts (torx in the center) before lifting – they can be difficult once the strut is unloaded.

    Front Coilover Install

    1. Disconnect the sway bar end link from the strut. Use a 5mm Allen key to hold the stud and a 16mm wrench for the nut. If the nut is frozen, apply penetrating oil the day before.
    2. Remove the three top strut mount nuts (13mm) from the strut tower under the hood. They may be accessed after removing the plastic cowl panel if applicable.
    3. Remove the pinch bolt at the lower knuckle (18mm or 21mm bolt). The knuckle often seizes onto the strut – use a ball joint separator or a hammer with a brass drift. Avoid damaging the axle boot.
    4. Slide the OEM strut out from the bottom. Compressing it slightly may help clear the knuckle. Transfer the top mount and bump stop to the new ECS coilover (some kits come with new top mounts).
    5. Install the new coilover into the knuckle and loosely thread the pinch bolt. Thread the top mount nuts by hand. Tighten the top nuts to 25 Nm, then torque the pinch bolt to 75 Nm plus 90 degrees. New hardware is recommended.
    6. Reattach the sway bar end link. Tighten while the car is on the ground under load.

    Rear Coilover Install

    1. Remove the lower shock bolt (14mm) and the upper mount (two 13mm nuts or a single 15mm bolt).
    2. Remove the rear sway bar end link from the control arm if it interferes.
    3. Compress the rear coilover slightly to clear the upper mount studs. Insert it into the tower and seat the lower eyelet.
    4. Torque the lower bolt to 70 Nm and the upper nuts to 25 Nm. Repeat on the other side.

    Ride Height Adjustments and Corner Balance

    Set the spring perches to achieve a 0.8‑1.0 inch drop initially. After lowering, bounce the suspension several times to settle the springs. Torque all control arm bolts with the car on the ground and the wheels loaded – rubber bushings bind if tightened at full droop.

    For serious handling, schedule a professional corner balance and alignment. Camber plates (available from ECS Tuning) allow up to -2.5 degrees front camber. A good alignment shop with a Hunter machine will dial in camber, toe, and thrust angle. For street driving, aim for -1.5 front / -1.0 rear camber with zero total toe.

    Upgrade 4: Sway Bar Kit for Flatter Cornering

    ECS Tuning’s adjustable sway bars reduce body roll without sacrificing ride quality as much as stiffer springs. The B9 S4 benefits from a 27mm front bar and a 22mm rear bar, both with multiple adjustment holes.

    Installation Overview

    1. Front bar: Remove the under tray and disconnect the stock end links. Unbolt the factory bar brackets (sometimes welded – if so, use ECS supplied brackets that utilize existing bolt holes). Install the new bar with bushings greased with supplied synthetic grease. Attach end links to the bar and control arm. Torque bracket bolts to 40 Nm, end link nuts to 50 Nm.
    2. Rear bar: Access after removing the spare tire well trim and underbody panels. The stock rear bar is removed similarly. The ECS bar often requires aftermarket end links (sold separately) for maximum adjustability.
    3. Set the adjustment: For street driving, use the softest hole (furthest from the bar side). For autocross or track, move to the stiffest hole (closest). Re‑torque after 100 miles once the bushings bed in.

    Post‑Installation Checks and ECU Adaptation

    Before the test drive, perform a visual walkaround. Check that all brake lines, ABS sensors, and wheel speed cables are secure and not rubbing against moving parts. Crank the steering lock‑to‑lock with the engine off and listen for any clashing.

    On the first start, allow the idle to stabilize. If you installed an intake, the ECU may learn the new airflow curve over a few drive cycles. Expect a slight hesitation at low rpm for the first 30 miles – this is normal as fuel trims adjust. For exhaust or intake systems, consider a software tune from a reputable shop like 034Motorsport to maximize gains and correct any CEL triggers. Tuning also raises the rev limiter and optimizes ignition timing.

    Performance Expectations and Real‑World Benefits

    With a cold air intake, cat‑back exhaust, coilovers, and sway bars, the B9 S4’s performance profile transforms. On a dyno, the intake and exhaust alone can add 15‑20 whp. Combined with a Stage 1 tune, you are looking at 420‑440 wheel horsepower – a significant increase over stock 353 whp.

    On the road, the car feels lighter on its feet. Body roll drops by 30‑50% depending on sway bar setting. The suspension tuning makes the car more eager to rotate on corner entry while maintaining composure on bumpy pavement. The exhaust note becomes purposeful without being obtrusive at highway cruising speeds.

    Keep in mind that lowering the car more than 1.2 inches may require adjustable control arms for the rear to prevent excessive negative camber and tire wear. ECS Tuning offers those as a separate upgrade.

    Conclusion

    Installing ECS Tuning upgrades on your B9 S4 is a systematic process that rewards careful work with genuine performance improvements. Whether you focus on induction, exhaust, suspension, or all four, each step reinforces the other. Take your time, follow provided instructions, torque every fastener, and after the final wheel is on, enjoy the result. Your S4 will respond with sharper throttle, flatter cornering, and a sound that matches its German engineering pedigree.

    For detailed product specifications and video tutorials, explore the ECS Tuning official site. The Audizine B9 S4 community is also an excellent resource for owner experiences and troubleshooting. Lastly, refer to the factory repair manual (found on sites like Erwin Audi) for torque specs that supersede generic values. Happy wrenching.