Here's the scoop

Front doors - will take 6.5" speakers - can only lock down 3 screws, but
that should be sufficient - autotech makes a spacer that will allow
window crank clearance with grilles

rear AC unit - will take 5.25" speakers cleanly.  the grilles will
*just* fit between the roof & the bottom lip of the A/C unit - kinda
awkward to cut though.  I had to file the last 3/4 inch instead of
sawing.... you could probably fit some 5x7" in there for a slight bit
more sound, but more $$$ & work to fit them in too....

yes - the stock speakers suck... a lot. no doubt about that at all.  the
stock deck is pretty crappy too.

Mark
87 Jammin Westy
84 tuneless scirocco

< I'm wondering if the stock speakers are as bad as they sound
 at increased volume levels, or if it's just the stock VW radio/cassette
that
 makes them sound that way.>

They are that bad. Any moderate amount of power and low frequency will
rattle
them to a quick and well deserved death.

I'm trying to figure out a clean install which will
1) use the existing wiring and holes in the AC unit.
2) improve the sound
3) not be obtrusive
4) not bring the ductwork down on someone's head

I have some ideas and will post results to the list as soon as I've
completed
the install

Paul 89 Carat 146K