HI all,      On the question of ignition timing I would urge you to use
caution when advancing the timing past specs.
When the timing is too advanced then "pinking" or "pinging" can occur which
is detonation too early and it can be damaging to your engine.     It will be
most noticeable at low rpm when accelerating.    I am leery of this with the
poor quality gas we sometimes encounter.
On the other side of this, VW probably retarded the ignition to meet
emissions specs and so the book timing is too retarded for maximum power.
Try advancing a degree at a time past 5 BTC and check for pinging.   Then
back off a degree or two if you encounter this.     When the engine is very
hot (too hot) this pinging will occur earlier.     In Europe, often 10
degrees BTC is used but the gas has a higher octane level.
Check the maximum advance too.    This should be about 30 degrees BTC or
perhaps a little more (vacuum advance disconnected).   Maybe another listee
has a more accurate figure for this.
As the vehicle spends most of its life at full advance, this is the figure
you want to get right.
Steve Cotsford