I'm not really sure how it works on a forced induction setup, but on an N/A it simply acts as a catalyst of sorts to help the fuel combustion. basicially it allows you to run a leaner mixture (leaner meaning less fuel burned and more power) without raising the temp of the combustion. With the leaner (also meaning faster) fuel burn the timing would need to be advanced to take advantage of the hydrogen assisted burn.

86 4runner, pro comp AAL, Kayline Soft top, 31's but all stock