It will be interesting to see how the output differs on a dyno with a greater reference point such as a dynojet to really make for a more solid comparison. The only point of reference applicable at this point would be that Kleemann rates the SLS M159 supercharger at 49 horsepower more than their M156 supercharger kit.
Weistec for their Stage I M156 supercharger with the 2.3 liter blower rates the output at 637 horsepower and 523 wheel horsepower. Interesting difference in the claimed ratings by Kleemann considering the boost levels and the numbers from the more efficient 2.3 liter twin screw versus the Magnuson TVS2300:
BenzBoost will bring you an in depth comparison on the superchargers in a separate article. Video below.