" Here is a great comparison featuring the best naturally aspirated V8 powerlpant in AMG's history going up against AMG's newer turbocharged design. The M159 V8 in the SLS Black Series is a 6.2 liter naturally aspirated V8 and this particular car is tuned by Weistec along with featuring long tube headers. As Weistec Engineering demonstrated last month their SLS Black Series tune with headers is good for over 600 horsepower at the wheels on 91 octane
The E63 AMG is a 2013 rear wheel drive model. This car has a tune from Renntech along with RADO downpipes said to be good for around the 630 wheel horsepower range. Torque is in the turbo M157's favor with 735 lb-ft at the wheels. The M159 by contrast has 463 lb-ft at the wheels which is a very large difference on paper. Nobody will deny turbocharged motors are capable of big torque numbers.
That said, the SLS Black Series features tighter gearing and a much higher redline at 8000 rpm. It's a motor with a definite breathing advantage at higher revs.
Power and torque are in the E63's favor (at a lower rpm) but the SLS Black Series is roughly 600 pounds lighter. The SLS also has a dual clutch transmission whereas the E63 is using the MCT wet-clutch automatic. "