When most tuners give a car gargantuan amounts of horsepower, they also equip it with a silly carbon-fibre bodykit, eminently kerbable wheels and a lavish interior. Mansory, Brabus, Novitec… we’re looking at you.

Posaidon is a bit different. Because while this Mercedes-AMG S63 Cabriolet looks entirely standard, under the bonnet it’s everything but. The 5.5-litre V8 (this is a pre-facelift car) has been bored-out to 6.3-litres, and many of its internal components strengthened or tweaked. The seven-speed automatic gearbox has been reinforced too, and there’s a new radiator to keep everything cool.

The result of all this tinkering? A not inconsiderable 991bhp and 1,400Nm. That’s 414bhp and 500Nm more than standard. A bit like squeezing whole Merc-AMG A45 under there. Gulp.

The tuning package, which Posaidon offers for any AMG fitted with the old 5.5-litre V8, means this S63 will hit 100kph in 2.9 seconds, and run on to a limited top speed of 350kph. Which is most definitely enough. Not least if the roof’s down.

There’s no word on pricing – but this much power rarely comes cheap. If you could, would you?