Lets back up for a moment...
We all know the saying "there is no substitute for displacement"...way back in the day the easiest way to increase horsepower was to increase the displacement of an engine. The displacement increase sort of stopped at around 7 liters (427 ci.in.) with a few exceptions.
The rule of thumb was that the larger the bore, the shorter the stroke, the more top end power, while a smaller bore with a longer stroke increased torque for any naturally aspirated engine.
We know that the Roots compressor from a 2 cycle Detroit Diesel (6-71 / 8-71) became and remains a hot rodding forced induction mainstay. Similar compressors are used today primarily by GM, Ford, Chrysler on several high performance models. Think ZL1, Z06, Hellcat to name a few.
If you are of a certain age, you remember the Oldsmobile Cutlass and Corvairs from 50 years ago with turbochargers. Back in the day, turbos were wonderful technology, driven from the exhaust, although the application and usage was "challenging" with the often mentioned "turbo lag" being a negative aspect.
Fast forward to today, with technology (computers) turbo's are dramatically better in real life with no "lag" and in many applications huge torque at lower revolutions.
As we mentioned a few years ago, engines are decreasing in cylinders and displacement while being enhanced with turbos. The old mantra of there is no substitute no longer applies. A V6 with a couple fo turbos generates the same power as a naturally aspirated V8 as an example.
Fuel economy and emission regulations are making 4 cylinders with turbos very popular from all manufacturer, notice all the CUV's with a forced induction 4 cylinder. Agreed...the multi speed (6+) automatic transmissions are also a factor in facilitating these 4 cylinder applications.
From our perspective we are in the "age" of forced induction. While it took a few years to arrive at this juncture its certainly here to stay for the foreseeable future.
We still believe that luxury vehicles must have a luxury engine.