That clearly shows the downpipes making a very nice difference. Torque figures rise from 667 pound-feet at the wheels to 766.19 with the downpipes. That is not a typo, that is a gain of almost exactly 100 pound-feet at the wheels. Very, very impressive.
The 93 octane pump gas figure shows a peak of 684 wheel horsepower for the tune and downpipes. The torque figure is basically the same as the 91 octane figure with a peak of 765 pound-feet at the wheels. The 93 octane fuel making a difference as rev climb past 4250 rpm allowing more peak horsepower. Below that RPM the torque is the exact same as on 91 octane.
Dyno graph and video below, great work by Weistec showing off the quality of their downpipe solution for the M157.