Timing advance-hp increases by what principles?

[SHOWMX@aol.com]

Can someone please explain how the hp increase, claimed by many CIS-E drivers,
is derived from ignition timing advance. It seems as though many Audi & VW
drivers have advanced their ignition timing from stock 6 degrees BTDC to 10-15
degrees BTDC and claim aprox 5+ hp dyno proven.  Where does this come from, or
how is it derived based on engine physics?

BTW, thanks to all Q-listers for answering my many questions and making this
the best, most informative board around!

Briand P.
'87 4000cs