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German tuner Posaidon turns its attention to the Mercedes-AMG A45 for the RS 525 that pushes the output to 518 horsepower (386 kilowatts or 525 metric horsepower). With this big boost in power, the hot hatch can allegedly hit 201 miles per hour (324 kilometers per hour).

The RS 525 upgrade gives the A45 a different turbocharger, revised engine mapping, and software adjustments to the eight-speed dual-clutch transmission. After these changes, the total output is 518 hp (386 kW) and 443 pound-feet (600 Newton-meters) of torque. In comparison, a stock A45 S has 416 hp (310 kW) and 369 lb-ft (500Nm) of twist.

Posaidon estimates the RS 525 package lets the hatchback reach 62 miles per hour (100 kilometers per hour) in 3.4 seconds, versus 3.9 seconds in stock trim.

Gallery: Posaidon Mercedes-AMG A45 With 518 HP

If you don't feel comfortable making extensive modifications like swapping out of turbo, then Posaidon offers a version of this kit that only involves software tweaks. With just these changes, the A45 makes 459 hp (342 kW) and 413 lb-ft (560 Nm). Acceleration to 62 mph requires an estimated 3.6 seconds, and the top speed is 198 mph (318 kph). 

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Posaidon is also teasing an even more powerful "Plus" tuning package that's still in development. The company isn't providing any details yet, but it's safe to guess that the output is even higher than 518 hp. The firm is also working on other performance improvements, like brake systems, exhausts, and carbon fiber wheels.

As an idea of what other tuners can do to the A45 and its siblings, Renntech offers kits that are capable of boosting the output as high as 592 hp (442 kW) by changing the turbo, exhaust, and engine control software. Without any mechanical tweaks, the company can increase the figure to 469 hp (349 kW).

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POSAIDON A 45 RS 525 (based on Mercedes-AMG W177 A 45 / A 45 S 4MATIC+)

High-speed hot hatch: POSAIDON A 45 RS 525 hits 324 km/h

By launching the A 45 and A 45 S – AMG siblings in the latest A-Class generation (W177) – Mercedes-Benz put two red-hot irons in the compact-class fire. The ex-works models boast 387 hp (A 45) and 421 hp (A 45 S) 2.0l engines with twin-scroll turbochargers, AMG SPEEDSHIFT DCT 8-speed dual-clutch transmission, plus 4MATIC+ all-wheel drive, turning these “little” AMGs into high-speed missiles.
All the same, the engineers at POSAIDON saw the need to boost the A 45’s performance even further. And, unlike their competitors – many of whom have only hinted at making such modifications – POSAIDAN have already launched a two-tier upgrade for the two A-Class siblings. What’s more, there are further projects in the pipeline!

In keeping with standard POSAIDON nomenclature, the workshop’s most powerful interpretation of the A 45s (to date) will go by the name A 45 RS 525. The name details the performance boost achieved by POSAIDON: By installing a more efficient, upgraded turbocharger and optimizing the engine map, the POSAIDON engineers have unlocked a hefty 525 hp in the M139 engine along with maximum torque of 600 Nm. Thanks to further optimizations to the control units for the AMG SPEEDSHIFT transmission and the drive chain (CPC), the A 45 converts this added power into a catapult launch, going from 0-100 km/h in just 3.4 seconds and topping out at 324 km/h. By way of comparison, these figures mean the hot hatch is as fast as the legendary Ferrari F40.

POSAIDON’s lower-tier upgrade is only tamer by a whisker; leaving out the turbocharger upgrading and focusing exclusively on the software optimizations detailed above, it generates 465 hp plus 560 Nm of torque. This upgrade tier achieves a top speed of
318 km/h and 0-100 km/h in 3.6 seconds.

Preparations for TÜV assessments are underway for both power levels. What’s more, as we alluded to earlier, an even more powerful “plus” model is currently in the development phase – though POSAIDON is giving nothing away at present about its potential performance. This summer, POSAIDON is also set to launch a host of extras for the AMG A 45 and A 45 S, including a high-performance braking system, cat back sports exhausts, turbochargers and – of course – its in-house, full-carbon Evolution One rims. Perfectly dimensioned at 8.5x20", these weigh in at just 4.9 kilograms each.

Incidentally, the POSAIDON power upgrades detailed here are also “suitable” for sister models of the A 45/A 45 S, namely the 45 models in the CLA series C118 (Coupé, four- door) and X118 (Shooting Brake) as well as H247 series compact SUVs, the GLA 45 and GLA 45 S. These all feature identical drive systems and are set to hit the market in May.

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