Audi A4 B9 Performance Mods
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The 5 Best Audi A4 B9 Performance Mods

Chandler Stark

Meet Trey

Trey is an automotive enthusiast and has a huge passion for Volkswagen and Audi vehicles of all kinds. His enthusiasm started with the MK5 GTI, and he has massively expanded his knowledge over the years. When Trey is not delivering high-quality and in-depth content, we can usually find him working in his garage on his modified Genesis coupe. Trey created VW Tuning several years ago, and he is the primary visionary behind the content.

Disclosure: This post may contain affiliate links, meaning when you click the links and make a purchase, we receive a commission.

The Audi A4 B9 is the successor of the A4 B8 and was first introduced in 2015 at the Frankfurt Motor Show. It was produced in 2016 and is still being produced today on the Volkswagen MLB Evo platform. This car came out with many different engine options: 35TFSI, 40TFSI, 45TFSI, 30TDI, 35TDI, 40TDI, and 45TDI. The 40TFSI, 45TFSI, 40TDI, and 45TDI can come with quattro®, which is Audi’s AWD system.

Ignition Coils & Spark Plugs

Before getting into the mods on this guide, let’s talk about ignition coils and spark plugs. Believe it or not, older ignition coils and spark plugs will dampen the engine’s performance dramatically. The factory coils and plugs are built for stock engine performance, and can’t sustain too much extra power. Unless you’re just wanting to buy bolt-on mods, not including tunes, factory coils and plugs should suffice. However, when you start modifying more than 30hp, you’ll want to get colder running coils and plugs. If they haven’t been changed in the last 10,000 miles, the true performance of the engine could be dampened.

Buy Here: Audi A4 B9 OEM Ignition Coils
Buy Here: Audi A4 B9 Spark Plugs

We’ll be focusing on the 2.0TFSI engine because it is the most common in the A4 B9. However, if you need assistance in looking for parts on another engine, reach out in the comments and we’ll give recommendations.

How to Make Your Audi A4 B9 Faster

To make your Audi A4 B9 a 350hp machine, you will need to add these aftermarket A4 B9 Mods:

  • Tune
  • Intake
  • Intercooler
  • Charge Pipe
  • Turboback Exhaust

Recommended Supporting Mod

  • GFB DV+

The mods listed above are in no specific order, however, if you are just trying to get a little more zip out of the engine, a tune and intake will add around 60hp. In this guide, we will be going over the performance benefits, gains, costs, and companies we recommend when modding out an A4 B9.

1. Audi A4 B9 Piggyback Tune

The biggest bang for your buck when it comes to mods is going to be a flash tune or an ECU upgrade. We see tunes as a great foundation for future modifications. Upgraded tunes don’t just offer power gains, but they also adjust the fueling, air-fuel ratios, increase boost targets, and overall make the engine more efficient. Factory tunes are made for comfort and aren’t optimized for the most power out of the engine.

Now there are a lot of tuning options on the market, but our favorite is the piggyback tune, JB4, from Burger Motorsports. What is a piggyback tune? It is essentially a “chip” that plugs directly into the ECU and tricks the factory tune into making more power. It does this by altering ignition timing, increasing boost, adjusting AFRs, etc. Now this JB4 offers up to 8 maps, meaning 8 different tuning setups, ranging from conservative to aggressive. Also, something worth mentioning is this tune doesn’t re-write the factory tune. So if you want or need to go back to stock, it is simple to accomplish.

Burger Motorsports JB4 – Audi A4 B9

Audi A4 B9 JB4

The JB4 features many benefits including easy installation, up to 8 tuning maps preloaded, not VIN locked, and many more. This tune increases the boost pressure 4psi over the stock turbo pressure, increasing power.

Price: $479
Audi B9 A4 Tune Power Gains: 45-65hp & 65-70lb-ft tq

2. Audi A4 B9 Upgraded Intake

After getting a tune, the best supporting mod would be an upgraded intake. An air intake brings in air from outside of a vehicle and brings it into the intake manifold. The factory intake is pretty restrictive when it comes to bringing air into the engine. Now, since you have implemented an upgraded tune, the engine will need more air airflow, which an upgraded intake will bring in typically 30% more air than the factory system. The performance benefits seen from an upgraded intake system include power gains, 30%+ airflow increase, quicker throttle response, faster turbo spool, and increased turbo efficiency.

Audi’s have always had pretty solid air intakes out of the factory, but they just simply can’t compete with an upgraded system. With an intake as a sole upgrade, expect to get 3-5hp tops. However, with a tune, not only will the engine see an increase of 10hp+ gains, but it will run more efficiently. With a tune, the turbo works harder with more power. So, an upgraded intake will bring in 20 – 30% more airflow to the engine which will put less pressure on the turbo, making the engine run more smoothly and reliably.

Open Air vs. Closed Box Air Intakes

When it comes to aftermarket air intakes, there are typically two choices: an open air intake or a closed box intake. Open air intakes are probably what you have seen in many engine bays, it is exposed in an engine bay. A closed intake will put the filter in a “box” so the intake is not breathing in hot engine air.

Typically open air intakes will yield higher airflow, which in turn will have higher power gains. Closed intake systems will provide less airflow, which means less power gains, but will provide cooler intake temps. Since the air coming in from the intake goes through the intercooler before going to the turbo anyway, slightly colder intake temps received from a closed intake system don’t make much of a difference. With that said, we lean toward open air systems because of the increased airflow yielding more power, and they are more aesthetically pleasing.

Integrated Engineering Performance Intake

The Integrated Engineering Performance intake system features a five-inch diameter filter, a heat shield, direct replacement to OEM unit, and many more. We’ve always been big proponents for IE products because of the high-end quality at a fraction of the price of other competitors.

Price: $379.99 + Free Shipping

3. Intercooler Upgrade

Intercoolers are always a hot topic of if they are worth it or not when it comes to modding out a vehicle. Our answer, they are 100x worth. Intercoolers are not only performance mods, they are also reliability mods. What does this mean? Upgraded intercoolers don’t provide too much power gains, but they provide cooler engine temperatures. Which in turn, increases and maintains power over time.

An intercooler reduces the intake air temps and increases the density of the air before going into the engine. The cooler and denser the air is, the more power the engine will get. Factory intercoolers are sufficient enough for factory conditions. However, once you start adding more mods, like a tune, the hotter an engine gets and the factory intercooler will quickly get overwhelmed. When an intercooler becomes overwhelmed, its functionality will start to diminish quickly and experience heat soak.

Heat soak is when an intercooler gets overwhelmed and can’t cool all of the air going through it efficiently and sends warmer air to the engine. When this happens, the engine will gradually lose power. Some vehicles with factory intercoolers experience a loss of up to 20whp due to heatsoak. Upgraded intercoolers not only reduce IATs, but also reduce pressure drop by up to 40%.

ECS Tuning Upgraded Intercooler

We like the Luft-Technik (ECS Tuning) intercooler because it is priced well and provides massive benefits to an upgraded engine. It features an increased bar and plate core, increased surface area, and a direct replacement to the factory unit. The performance benefits seen are truly eye-opening and will make the engine of an Audi A4 B9 much more efficient: 105% improved efficiency, reduce IATs by as much as 65°F, and reduces pressure drop by 47%.

Price: $520.16 + Free Shipping
Intercooler + Charge Pipe Kit: $622.76 ($98 or 13% in savings when bought together)

4. Audi A4 B9 Charge Pipe

The factory charge pipes generally should be replaced when an aftermarket intercooler is put on an engine. Charge pipes are the pipes that connect the intercooler to the intake manifold. An aftermarket intercooler has many benefits as you have read from above, but to get the full effect of your new intercooler, you’ll want to upgrade the factory charge pipes as well. Like the intercooler, charge pipes do provide slight power gains, but are more for engine reliability.

The factory charge pipes are made of plastic with rubber couplers. These factory pipes can only really handle the stock boost pressure. So once, you have a tune, intake, and intercooler, as you can imagine the factory charge pipes will be far more restrictive because they won’t be able to handle the increased boost and power. Remember, the goal is to increase airflow into an upgraded engine because it would yield more power.

ECS Tuning’s high flow charge pipe kit features a 2.75″ piping made with aluminum and silicone couplers. Not only is this kit more reliable for an upgraded engine than the factory kit, but also far less restrictive.

ECS Tuning High Flow Charge Pipe Kit

Charge Pipe Kit Price: $201.41
Intercooler + Charge Pipe Kit: $622.76 ($98 or 13% in savings when bought together)

5. Aftermarket Turboback Exhaust

Many people may be questioning why an exhaust is listed in the “The 5 Best Audi A4 B9 Performance Mods”, but we’ll go into it here. Aftermarket exhausts don’t necessarily provide the most power benefits, but it turns heads. To us, we love an aggressive sounding car that will make others wonder what’s under the hood. Sound aside, it does actually provide some benefits: reduces backpressure with the increased diameter, quicker throttle response, and improved fuel economy.

The reason we have “turboback” exhaust is because it includes the downpipe, which is where a majority of the performance benefit comes from in an exhaust. A catback exhaust goes from the downpipe to the tips and it doesn’t upgrade the factory catalytic converter, which is where most of the airflow restrictions happen. A downpipe connects the turbo to the rest of the exhaust. The factory downpipe houses the primary (very-restrictive) catalytic converter for emissions purposes, not for performance.

Therefore, with a turboback exhaust you will actually see some horsepower gain (10-20hp) when paired with a tune. In fact, the ECS Tuning system below saw peak gains from the exhaust of 16whp and 17lb-ft of torque. It features a high flow catted downpipe, 3″ tubing with 1.25mm thickness, interactive valved mufflers, and direct replacement to the factory exhaust system.

ECS Tuning Turboback Exhaust

Price: $1,662.56 + Free Shipping

Here’s a sound clip for the audio lovers out there. We love the sound of this system and it will certainly turn heads on the road.

Audi A4 B9 Supporting Mods

As the title says, the mod below is a supporting mod. These aren’t necessarily needed, but they are recommended for the auto junkies out there.

6. Upgraded Diverter Valve

A diverter valve is typically located on the side of a turbo and it diverts unused turbo pressure back into the engine preventing compressor surge. There’s nothing worse than doing a pull just to have the diverter valve prematurely open and lose boost pressure (ie turbo flutter). Factory valves can only sustain so much boost, that’s where upgraded diverter valves come into play. With an upgraded tune, most times boost pressure is increased, which means you will want to get an upgraded dv that can hold the increased boost.

The factory dv’s have diaphragms that are prone to failure at 20,000 miles. So not only would an aftermarket dv, like the one linked below from Go Fast Bits, be able to sustain increased boost, but it will last much longer because of the metal components it is made out of.

Go Fast Bits Audi A4 B9 Diverter Valve

Price: $143.10 + Free Shipping

Conclusion – Audi A4 B9 Performance Mods

With all of the mods listed above, you can expect to hit 350hp easily. Again, the full turboback exhaust is not necessarily needed, we added it due to the sound. However, if you don’t want to do the full exhaust for cost purposes, an aftermarket downpipe (Catless or Catted) will still be very beneficial for performance. Happy modding and let us know what your setup looks like in the comments below!

If you want to read more about the A4 B9, here’s a post on The 6 Most Common Audi A4 B9 Engine Problems.

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