Testing with an Arrow 'intermediate' system, (it replaces the cross-over and pre-mufflers, as well as the mufflers) has shown a result more like what is commonly expected. (Improvements!)
The results of a more recent test with an Arrow intermediate system, tell a different story.
The 'drop-on' test used a different chip for WOT fuel, but the same ignition curve.
With the huge variation in 'out-of-the-box' cam timing one can expect a large variation in results with a drop-on only.
The greatest improvement comes with arranging for both cylinders to be on the 'same page', or working together, (the red trace.)