Mercedes-AMG is quite proud of the fact that its outgoing M133 2,0-litre turbocharged engine is the most powerful production four-cylinder unit in the world. And the tuners over Posaidon have now shown just how far this four-pot can be stretched.

The hot hatch’s boosted engine now sends a whopping 405 kW and 660 N.m of torque to all four corners via its seven-speed dual-clutch transmission. That's significantly more than the standard model’s 280 kW and 475 N.m of torque. Interestingly, Posaidon says it has limited the torque figure in a bid to preserve internal components.

How were these lofty figures achieved? Well, the German firm upgraded the turbochargers, air cooling system, spark plugs, air intakes and exhaust system, before adding a water-methanol injection system and remapping the ECU. Revisions to the transmission were predictably also made, with Posaidon adding that further tweaks (to allow the gearbox to handle more than 660 N.m of torque) will soon be offered.

Unfortunately, the tuner haven’t provided any details about the hot hatch's new performance figures, but we're guessing this special A45 is much faster from zero to 100 km/h than the standard model, which completes the obligatory dash in 4,2 seconds.

Of course, the next-generation A45 is firmly on the horizon, with the head of the Affalterbach-based brand already confirming a figure of more than 300 kW from a “brand new” 2,0-litre four-cylinder unit.