B9.5 Audi S5 Sportback 3.0T Maintenance & Upgrade Log

As another small exterior update, we replaced the factory mirror turn signals with CAP Dynamic Mirror Turn Signals.

The turn signals completely replace the original mirror turn signals and change the standard lighting pattern to a sweeping dynamic signal.

It’s a relatively subtle modification compared to the larger exterior changes already made to the S5, but it adds a more modern lighting detail to the side mirrors and helps continue refining the smaller details of the build.

The original hood was one of the major exterior panels damaged in the S5's front-end collision. The damage was severe enough that once the bumper was installed, the hood would no longer close properly and had to be reshaped just to get the front end aligned.

With the rest of the front end now coming together, it was finally time to replace it.

Rather than going back to another factory hood, we installed a CAP Carbon Fiber Vented Front Hood.

The exposed carbon ties into the dry carbon fenders, mirror covers, spoiler, side skirts, and rear diffuser already installed throughout the project, while the vented design gives the front end a much more aggressive look.

At this point, one of the largest remaining pieces of visible collision damage was finally gone and the rebuilt front end was getting much closer to its finished form.

With the major collision repairs mostly behind us, we continued working around the exterior to bring the different areas of the project together.

CAP GLOSS BLACK FRONT LIP

The RS5 style front bumper was already a major change from the damaged factory S5 bumper, but the lower section of the front end was still missing a finishing piece.

We installed a CAP Gloss Black Front Lip, adding more definition to the bottom of the RS5 style bumper and giving the front end a lower, more aggressive appearance.

CAP CARBON FIBER SIDE SKIRTS

Next, we added CAP Carbon Fiber Side Skirts.

With exposed carbon already on the fenders, mirrors, and spoiler, the side skirts helped carry the carbon theme across the full side profile instead of concentrating it only around the front and rear of the car.

CAP CARBON FIBER DIFFUSER V1

The factory rear diffuser was then replaced with the CAP Carbon Fiber Diffuser V1.

Adding carbon to the lower rear end helped tie the diffuser into the V3 spoiler and the rest of the exterior carbon while giving the back of the S5 a more aggressive finish.

With the front lip, side skirts, and diffuser installed, the exterior was starting to look consistent from front to back.

With the intercooler and charge pipes already upgraded, we continued improving the intake and charge-air system in preparation for the additional power planned later in the project.

CAP 8" INTAKE V2

We replaced the factory intake with the CAP 8" Intake V2 for the B9/B9.5 Audi S4/S5.

Aside from increasing airflow into the turbo, one of the biggest changes was the sound. The larger intake brings out significantly more turbo spool and induction noise that is muted by the factory system.

With future tuning already planned for the S5, upgrading the intake also gave us a better foundation for the increased airflow demands that will come with making more power.

CAP TITANIUM TURBO INLET V2

Next, we installed the CAP Titanium Turbo Inlet V2.

With the intake upgraded, it made sense to continue improving the airflow path into the turbo rather than leaving the factory inlet in place. The titanium construction also adds another functional and visual upgrade to the engine bay while pairing with the rest of the CAP intake setup.

CAP POST THROTTLE VALVE TITANIUM CHARGE PIPE KIT

We finished the airflow upgrades with the CAP Post Throttle Valve Titanium Charge Pipe Kit.

This continued the upgraded charge-air system beyond the throttle valve and added another titanium component to the setup, complementing the CAP intercooler and charge pipes installed earlier in the project.

Together, the intake, turbo inlet, and post-throttle charge pipe moved the S5 another step closer to being ready for future tuning.

The S5 was purchased without its front fender liners, another component left missing after the collision.

With the dry carbon fenders, replacement impact bar, and RS5 style bumper now installed, we could finally finish the front wheel wells by installing the missing fender liners.

It wasn't one of the flashy upgrades of the project, but it was an important part of properly putting the car back together. The liners close off the wheel wells and restore the protection that had been missing since we purchased the vehicle.

This checked off another remaining piece of the original collision repair and brought the S5 closer to being completely rebuilt.

With the major collision repairs almost complete and the S5 finally getting back on the road, it was time to take care of one of the most important baseline maintenance items — its first oil change since joining the CAP fleet.

ENGINE OIL & FILTER CHANGE

Instead of draining the oil from underneath the car, we used an oil extractor to remove the old oil through the engine bay. This makes the service cleaner and allows the oil to be changed without lifting the vehicle or removing the underbody panels.

With the old oil extracted, we replaced the oil filter and refilled the 3.0T EA839 V6 with approximately 7.3 litres of Liqui Moly Top Tec 6200 SAE 0W-20.

Starting with fresh oil and a new filter gives us a known maintenance baseline as the S5 moves into more performance upgrades and eventually increased power.

SERVICE SUMMARY

Service Reset: Audi MMI
Oil Used: Liqui Moly Top Tec 6200 SAE 0W-20
Oil Capacity: Approximately 7.3 L
Drain Method: Oil extractor
Oil Filter: Hengst Filter
Engine: 3.0T EA839 V6

With most of the major front-end work completed, attention started shifting toward the overall appearance of the S5 and adding more exposed carbon throughout the exterior.

CAP V3 DRY CARBON FIBER SPOILER

For the next exterior upgrade, we let the people following the build make the choice. We asked followers to decide between the CAP V1, V2, and V3 Dry Carbon Fiber Spoilers, and the V3 came out on top.

The existing spoiler was removed and the mounting surface was thoroughly cleaned and prepared before installing the CAP V3 Dry Carbon Fiber Spoiler using double-sided tape.

CAP uses 3D scanning during product development to closely match the factory mounting surface, helping the spoiler follow the shape of the trunk for OEM-level fitment without drilling into the car.

CAP DRY CARBON FIBER MIRROR COVERS

To continue the carbon theme throughout the exterior, we also installed CAP Dry Carbon Fiber Mirror Covers in place of the factory covers.

The exposed carbon adds another detail to the side profile while tying in with the dry carbon fenders and V3 spoiler.

The passenger-side headlight was another expensive casualty of the front-end collision. A complete replacement assembly can cost around $4,700 USD, largely because of the amount of electronics and lighting hardware contained inside it.

Fortunately, the internal components survived. The main damage was to the outer lens and housing, so instead of replacing the entire headlight, we transferred the original internals into a replacement housing.

Since the headlight was already apart, we took the opportunity to customize it by blacking out the internals and installing demon eyes.

What started as a necessary collision repair ended up becoming one of the most distinctive details of the rebuilt front end.

The front-end collision damaged several of the S5's exterior and structural components. Rather than simply returning everything to stock, we used the rebuild as an opportunity to start changing the appearance of the car.

CAP RS5 STYLE FRONT BUMPER

The original S5 front bumper was heavily damaged and needed to be replaced.

Instead of installing another factory S5 bumper, we upgraded the front end with a CAP RS5 Style Front Bumper, giving the car a much more aggressive, RS-inspired appearance.

CAP DRY CARBON FIBER FENDERS

The passenger-side fender was also damaged in the collision. Rather than replacing only the damaged panel with another factory fender, we removed both original fenders and installed a set of CAP Dry Carbon Fiber Fenders.

This replaced the damaged panel while also becoming one of the first major carbon fiber upgrades of the project.

IMPACT BAR REPLACEMENT

The original front impact bar had also been affected by the accident, with its supporting mounts broken off.

We sourced a replacement impact bar from a B9 Audi A4 part-out, painted it black, and installed it in place of the damaged original so the front end could properly go back together.

The accident damaged both the radiator and factory intercooler, making the cooling and charge-air systems some of the first major mechanical areas that needed attention.

Since the front end was already apart, we also used the opportunity to begin preparing the 3.0T EA839 for future performance upgrades.

CAP ALUMINUM CHARGE PIPES

With the CAP Intercooler already installed, we replaced the factory plastic charge pipes with CAP Aluminum Charge Pipes.

The S5 remained on its stock tune at this stage, but with plans to increase power later in the build, upgrading the charge pipes now meant we wouldn't have to rely on the original plastic piping once boost levels increased.

ENGINE COOLANT FLUSH

When the replacement radiator was initially installed, the cooling system had to be refilled. We later decided not to leave the coolant used for the initial refill in the car long-term, so the system was drained and flushed.

We drained and flushed the cooling system before refilling it with OEM Audi G12EVO coolant, giving us a known coolant baseline moving forward.

OEM RADIATOR & CAP INTERCOOLER

The damaged radiator was replaced with an OEM replacement, but rather than installing another factory intercooler, we used the opportunity to upgrade to a CAP B9/B9.5 Audi S5 Intercooler.

The CAP unit features a bar-and-plate core, cast-aluminum end tanks, and over 135% more volume than the OEM intercooler, helping reduce intake-air temperatures and pressure drop as power levels increase.

Since the factory intercooler already needed to be replaced and we planned on making more power later in the build, upgrading it now made much more sense than going back to stock.

On April 2, 2026, we purchased this 2021 B9.5 Audi S5 Sportback 3.0T from auction with 118,675 km on the odometer.

The S5 had been involved in a front-end collision and had an estimated $26,585 in damage. Before any performance upgrades, fitment testing, or product development could begin, the first step was documenting exactly what we were starting with and determining what would be required to bring the car back to proper condition.

S5 PURCHASE SUMMARY

Vehicle: 2021 B9.5 Audi S5 Sportback 3.0T
Mileage: 118,675 km
Condition at Purchase: Front-end collision damage
Estimated Repair Cost: $26,585

COLLISION DAMAGE

The majority of the damage was concentrated around the front end of the vehicle.

• Front bumper damaged
• Hood damaged
• Passenger-side headlight damaged
• Passenger-side fender damaged
• Radiator damaged
• Intercooler damaged
• Front impact bar damaged
• Fender liners missing
• Lower splash guard missing
• Passenger-side ACC wiring cut

NEXT STEPS

With the initial damage documented, the first priority was restoring the S5 to proper mechanical condition and replacing the damaged or missing front-end components. Once the car was back together, we could begin moving into the performance and exterior upgrades planned for the project.