The Mercedes-AMG S 63 Cabriolet was on the receiving end of an extensive tuning upgrade courtesy of Posaidon. The German tuner’s program was developed for the pre-facelift version of the AMG S 63. It’s the same model that uses AMG’s old 5.5-liter twin-turbo V-8 engine, which produces 577 horsepower and 664 pound-feet of torque. With the upgrades in tow, the AMG S 63 Cabriolet is now able to produce a whopping 1,005 horsepower and 1,033 pound-feet of torque.

Exterior

Posaidon’s program for the Mercedes-AMG S 63 Cabriolet covers the preceding model before the 2017 facelift. Still, there are a few notable upgrades in this section, one of which is a new set of wheels for the mighty AMG four-seater convertible.

Interior

The interior of the AMG S 63 Cabriolet follows a similar outlay. Either way, it’s not going to take anything from Poseidon’s program, which is really all about the cabriolet’s power and performance capabilities.

Powertrain

Some of you might be disappointed by the lack of meaningful exterior and interior upgrades that Posaidon is offering. That’s fair. It’s also fair to point out that Posaidon is making up for it with what can only be described as one of the most bombastic power bumps for this specific model.

Doing so required the reinforcement of a number of engine hardware, including the steel bushings for the cylinders. Likewise, updates to the main bearing line were done. The tuner also tweaked the engine’s compression ratio and reinforced the valve springs.

That’s not all. The V-8’s two turbochargers were also modified to accommodate the power bump. Posaidon even fitted a custom air kit, a new sports air filter, and a new radiator to get its achieve its desired power increase. Even the engine’s electronics layout had to be modified. The same holds true for the cabriolet’s differential locks and the seven-speed automatic transmission.

You’re probably wondering why Posaidon went through all this work. The reason is simple; the tuner wanted to give the AMG S 63 Cabriolet one of the biggest and most incredible power and performance upgrades you’ll ever see.

Do the math, and that adds up to almost 400 horsepower and 400 pound-feet of torque more than the standard AMG unit. Thanks to all that extra power, the cabriolet can now sprint from 0 to 60 mph in just 2.9 seconds, an improvement of one full second compared to the standard AMG S 63 Cabriolet. The car’s top speed also increased to 218 mph.

For a bit more context, German tuner prepared its own program for the same pre-facelift AMG S 63 Cabriolet back in 2016. At that time, the Brabus 850 6.0 Biturbo Cabrio was described as the fastest and most powerful cabriolet in the world. It produced 838 horsepower and 848 pound-feet of torque, good enough to propel the AMG S 63 from an idle position to 60 mph in 3.9 seconds to go with a top speed of 217 mph. Seems pretty slow by comparison now, right?

Pricing

The price of Posaidon’s bonkers engine upgrade for the AMG S 63 Cabriolet is on a need-to-know basis. You’re going to have to contact the tuner directly to get a proper quote on how much you’re going to have to spend. As foreboding as that sounds, don’t expect the kit to cost the equivalent of a brand new Mercedes.

Here’s some good news, too, for those who don’t get a Mercedes AMG S 63 Cabriolet. So if you have an older-generation CLS 63, E 63, ML 63, GLE 63, or G 63, the German tuner can accommodate your wishes of driving a car with four-digit power sitting under its hood.

Conclusion

Posaidon’s engine upgrade program is definitely not for the weak-of-heart. It’s definitely not for those who want to make their S 63 AMGs look prettier. The program was developed for one specific purpose: power, power, and more power.

If that’s what you’re looking for, then your search stops here. It’s not often that you see this kind of power on a Mercedes — the Project One obviously doesn’t count — so when it becomes available, you jump at the chance to get it.

Further reading

Read our full review on the 2018 Mercedes-AMG S63 Convertible.

Read more Mercedes-Benz news.