If you own a Mercedes-Benz E63 AMG and have considered tuning it, the name APR likely came up. The APR E63 AMG Performance Package, priced at $4,500, promises a dramatic transformation—more horsepower, sharper throttle response, and a more aggressive soundtrack. But for that kind of money, you could also invest in a set of lightweight wheels, a track day season pass, or even a down payment on a second car. Owner opinions on the kit are split, and the decision ultimately comes down to what you value most: reliability, warranty peace of mind, or raw acceleration. Let’s break down every angle—technical details, real-world owner reports, and alternatives—so you can decide if the $4,500 price tag makes sense for your E63 AMG.

Understanding the APR E63 AMG Performance Package

APR is a well-known aftermarket tuning company with a strong reputation for quality and consistency. Their E63 AMG Performance Package is not a single product but a bundled set of modifications designed to unlock power that Mercedes left on the table. According to APR’s official documentation and independent dyno tests, the package typically delivers a 120–150 hp increase and up to 160 lb‑ft of torque gain at the wheels on pump gas (93 octane). The power curve is smoothed out, mid-range torque is fattened, and the car pulls harder all the way to redline.

What’s Included in the Package

Unlike some tuners that only provide a flash tune, APR’s Performance Package for the E63 AMG (specifically the M157 engine used in the 2014–2018 E63 S) usually comprises several key components:

  • ECU Tune: A reflash of the engine management system that raises boost pressure, adjusts ignition timing, and optimizes air‑fuel ratios. APR offers multiple octane options (91, 93, 100, and even E85).
  • Downpipes (Optional but Common): Many owners bundle APR’s downpipes to reduce backpressure and improve spool. The package often includes high‑flow catalytic converters or cat‑delete pipes.
  • Intake System: A high‑flow intake increases airflow to the twin‑turbochargers, often made with a sealed carbon fiber housing to keep induction temperatures low.
  • Intercooler Upgrade (Sometimes): For cars that experience heat soak on track, APR may recommend a larger intercooler core, but this is not always part of the $4,500 kit.

The exact contents can vary by generation and seller, but the core is always the ECU calibration. APR also provides a hand‑held programmer or dealer‑level flash tool that lets you switch between stock and performance tunes, which is a feature many owners appreciate.

Real Numbers: What Gains to Expect

Independent dyno runs posted on MBWorld and other Mercedes forums show that a stock 2014 E63 S makes about 520–540 wheel horsepower. After the APR tune (Stage 1, 93 octane, no downpipes), that figure climbs to 660–680 whp. With downpipes and fuel system upgrades, Stage 2 cars can see 700+ whp. That is a substantial jump—roughly a 25–30% increase. At the track, owners report quarter‑mile times dropping from the low 11s to high 10s, often trap speeds going from 124 mph to over 132 mph. That kind of performance puts the E63 AMG in supercar territory, at least in a straight line.

Owner Experiences: The Good, the Bad, and the Mixed

The only way to really judge a $4,500 upgrade is to listen to those who have lived with it. We aggregated feedback from two major owner communities: 6SpeedOnline and the E63 AMG Facebook groups. The consensus is not uniform—while many owners rave about the transformation, a minority express buyer’s remorse.

Positive Feedback: “The Car Feels Alive”

Many owners describe the APR package as the single most transformative mod they have made. Common themes include:

  • Throttle Response: The tune sharpens tip‑in so that the car feels instant, not laggy. One owner on MBWorld said, “It’s like a different engine—power comes on with the slightest press of the gas.”
  • Low‑End Torque: The log‑shaped torque curve from stock is replaced with a plateau of massive torque from 2,500 to 5,500 rpm. That makes daily driving more relaxing because you rarely need to rev it out.
  • Sound Quality: The APR intake and downpipe combo (if chosen) gives the V8 a deeper, more guttural growl without being obnoxious on the highway. Several owners call the sound “addicting.”
  • Consistency: APR tunes are known for being safe; they run rich on the dyno and leave a margin of safety. Many owners have put 30,000+ miles on the tune with zero issues.

Negative Feedback: “I Wish I’d Known”

Not everyone is thrilled. The criticisms fall into three main categories:

  • Price vs. Gain: “$4,500 for a tune, an intake, and downpipes feels expensive when other tuners charge $2,000 for a similar setup,” wrote one owner on Reddit’s r/AMG. While APR’s reputation and support are part of the cost, some feel the value isn’t there when you can get a custom dyno tune for half the money.
  • Warranty and Dealer Issues: Several owners reported that their Mercedes dealer flagged the ECU as “tampered” during a routine service visit. Even though APR offers a “stock reflash” feature, some dealers still detect the number of flash cycles or a TD1 code. That can void your powertrain warranty—a critical concern for cars that still have factory coverage.
  • Cooling Concerns: On hot days or during repeated pulls at the track, some owners saw intake air temperatures skyrocket and the tune pull timing. Without an upgraded heat exchanger, the car gets heat‑soaked and loses performance. One owner on 6SpeedOnline had to stop using the tune after three aggressive highway on‑ramp pulls because the car went into limp mode. APR later released an intercooler kit, but it’s an extra cost.

The Mixed Middle

Many owners fall somewhere in between: they love the power but caution that the package is not a set‑and‑forget solution if you drive hard. “You can use it on the street all day with no problems, but track drivers need to budget for cooling mods,” said a forum moderator who runs an APR‑tuned E63 S. That honest feedback is valuable for potential buyers to set expectations.

Technical Deep Dive: What the Tune Actually Changes

To understand whether $4,500 is justified, you need to look under the hood—not just at the sticker. The M157 engine in the E63 AMG is a twin‑turbo 5.5‑liter V8. Stock boost is around 14–16 psi. APR’s calibration raises peak boost to about 20–22 psi, depending on octane. That almost doubling of boost pressure is what makes the car hit so hard. However, it also means the engine, transmission, and cooling system are under higher stress. APR compensates by adjusting fuel trims, pulling timing at high rpm, and maintaining safe exhaust gas temperatures. Independent data loggers have shown that APR tunes keep lambda values in the safe region (0.75‑0.80) under full throttle, which prevents detonation.

Still, the upgraded intake and downpipes are not just for noise—they are necessary to support the additional airflow. The stock intake has two small air filters with restrictive snorkels, and the stock downpipes have a single small catalyst. By replacing them, the engine can breathe freely, leading to faster spool and less turbo lag. If you skip these hard parts and just flash the ECU, you might leave 30–40 hp on the table and risk over‑spinning the turbos—APR’s kit bundles them for a reason.

Cost‑Benefit Analysis: Breaking Down the $4,500

Let’s put the price in perspective. Here is a rough breakdown of what you are paying for:

  • ECU Tune (hardware + license): ~$1,500–$2,000 (including the programmer)
  • Downpipes (cat‑delete or high‑flow): ~$1,200–$1,800
  • Intake system: ~$800–$1,200
  • Labor (if installed at a shop): ~$400–$800
  • Total if purchased separately: $3,900–$5,800

So the bundled price of $4,500 is roughly in line with buying the parts individually, but you gain the peace of mind that everything is calibrated together. Plus, APR provides a two‑year warranty on the parts and tune (excluding labor). If you compare that to a custom dyno tune from a local shop for $800 plus $1,000 in downpipes, you can see why some balk. However, APR’s tunes are thoroughly tested across climates and altitudes—a factor that matters for long‑term reliability.

From a dollars‑per‑horsepower perspective, say you gain 140 whp from the full package. That works out to about $32 per horsepower. That is actually decent value in the high‑performance tuning world. For comparison, a simple cat‑back exhaust might give you 10 hp and cost $2,500 – that is $250 per horsepower, nearly 8x less efficient. So for the power increase, $4,500 is reasonable.

Alternatives: Other Ways to Spend $4,500 on an E63 AMG

Before you commit, consider these alternatives that deliver similar or different benefits:

1. Renntech Stage 2

Renntech is the gold standard for Mercedes tuning, but they are even more expensive. A Stage 2 package with downpipes and a tune often exceeds $6,000. However, Renntech is Mercedes‑friendly and provides a full warranty through participating dealers, which may appeal to owners who want to keep their car under factory coverage.

2. Weistec Engineering Tune

Weistec offers aggressive tunes that push the M157 to 750+ whp. Their packages start around $3,500, but you often need their upgraded turbos and intercooler for reliability, which pushes the total much higher. Their tunes are more track‑oriented.

3. Custom Dyno Tune + Part‐Out

You can buy a set of used downpipes ($500–$700), a generic intake ($400), and have a tuner like Eurocharged or Tune‑Performance flash the ECU locally for about $800 total. Total cost: ~$1,800. You lose APR’s support and calibration breadth, but many owners report great results. The trade‑off: potential for hot tune, no backup warranty, and no ability to flash back instantly.

4. Invest in Suspension and Tires

If your goal is overall driving enjoyment, consider spending $4,500 on coilover suspension (e.g., KW V3) and a set of Michelin Pilot Sport 4S tires. The E63 AMG is already extremely fast—improving the chassis may give you more real‑world smile per dollar. Many owners who did both say the handling mods made the car more fun on winding roads than pure engine power.

Reliability and Warranty: What You Need to Know

The biggest hesitation for many is the impact on warranty. Mercedes has become more aggressive at detecting ECU flashes. Even if you return the car to stock, the dealer can see the number of flash cycles from the ECU’s logging. Some dealers are lenient; others will void your powertrain warranty for any engine or transmission issue after a flash. If your car is still under factory warranty, think twice. One owner shared that his dealer voided a warranty claim for a failed turbo seal, citing the APR tune as the cause—a $6,000 repair.

On the reliability front, the M157 engine is generally robust, but it has known weak points: the oil separator, timing chain tensioners, and turbo seals. Adding more boost can accelerate wear on these parts. APR includes a safety buffer, but no tune extends component lifespan. If you plan to keep the car beyond 100,000 miles, budget for potential repairs. Some owners have run APR tunes for over 50,000 miles without issues, but there is variance.

Final Verdict: Is It Worth $4,500?

After weighing owner experiences, technical data, and alternatives, the answer is not black and white. Here is a framework to decide:

  • Yes, if: You are not under factory warranty, you daily drive the car and want a smooth, powerful calibration, you appreciate APR’s reputation and support, and you can budget for potential cooling upgrades if you plan to track the car.
  • No, if: Your car is still under warranty and you are risk‑averse, you are happy with the stock performance (which is already immense), you prefer to spend money on handling or interior upgrades, or you are willing to piece together a cheaper custom tune.
  • Maybe, with caution: If you want supercar acceleration for a fraction of the price, but you are willing to accept a moderate risk of reliability issues or dealer warranty friction. Many owners fall into this camp—they love the power and accept the trade‑offs.

One final piece of advice: if you are leaning toward the APR package, call your local Mercedes dealer and ask outright how they handle flashed ECUs. Some are more friendly than others. Also, search forums for owners in your region—local tuners can sometimes install and support the kit. With careful research, $4,500 can turn your E63 AMG into a genuine beast. But if you’re not ready for the potential headaches, you might be happier leaving it stock and simply enjoying one of the best performance sedans ever made.