How about this experiment for HHO:
Measure the output of the device (Route the bubbles into a submerged, inverted container). simple math will account for the ratios of H2 and O2 produced (by volume.)
Use flow metered H2 and O2 from industrial tanks and insert that mixture into your intake.
See if it really makes a difference.
(If you don't like your engine, try just adding a little O2 by itself.)
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