Mercedes-AMG threw people for a loop when they stated the 2019 Mercedes-AMG C43 which receives a bump in output to 385 horsepower and 384 lb-ft of torque has larger turbocharger. AMR Performance later stated the newer C43 M276 V6 in fact utilizes the same turbocharger it always has.

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Some still believed the Mercedes-AMG claim as why would Mercedes-AMG get their own car wrong?

Click here to enlarge Originally Posted by AMG
The AMG-enhanced 3.0-liter V6 biturbo engine boasts a high power output combined with low fuel consumption and emissions. The high power output is in part courtesy of separate, larger turbochargers (max. charge pressure 16 psi). Installed close to the engine, the two turbochargers are especially spontaneous in their response. The AMG power unit can be identified by the engine cover with red aluminum insert and AMG lettering.
The larger turbocharger comment really should read more boost.

AMR delved further into this topic with data testing:

Click here to enlarge Originally Posted by AMR
The new 2019 Mercedes-Benz C43 AMG 4-Matic comes with the 3.0L BiTurbo V6 engine that we have been accustomed to in its pre-19 C43 AMG vehicles. However, the new model comes with a new face-lift consisting of a new designed grille, revised front bumper, revised rear bumper, a new wheel design and some changes to the interior as well, giving the vehicle a new look. With the new look comes some changes to power. The new model has a bump in power from the advertised 2017-2018 models at est. 367hp to a new est. 385hp.

This new power has created quite the buzz. From speculation of larger turbochargers to just adjustments made to the vehicles ECU software. AMR Performance engineers were able to take a deeper look into the vehicle's ECU logic and mapping as some data acquisition (data logging) done in-house on our DynoJet 424xLC2 dyno.
So what accounts for the output change?

Click here to enlarge Originally Posted by AMR
Our engineers monitored the ECU's data acquisition which showed very small changes to ignition timing and fueling but nothing major enough cause a power effect giving the true statement that the BOOST increase was giving factor to the additional power gains
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More boost and some ignition timing changes. The boost profile also looks quite a bit different.

Thank you to AMR Performance for providing this data and further research on the topic.