questions on buying used Audis...

[steve@ipecac.engr.sgi.com (Steve Valin)]

I'm trying to figure out what used Audi to get and I have a
few questions.  I know about the archive, but has anyone tried
to find info in this thing?  I'd have to take a week off to 
read thru everything!

1.  I've been looking at '86-'87 4000Q's and noticed that they
    all use KE-Jetronic, an electonic/mechanical combo.  Most 
    manufacturers had switched to J-Jetronic by then.  How 
    reliable is it?

2.  Does anyone have any pointers to articles on how to tweak
    these engines from this era?  How about things to look for
    when looking to buy a '85-'87 4000/5000?

3.  For the '88-'91 80's and 90's, my impression is that they are
    basically the same car with different engines and trim levels.
    The 80Q and 90Q appear to have the same drivetrain, though.  
    What's the difference between these two models?

4.  Does the 20V engine have any identifying labels?  Is it a 
    twin cam?  Are the plugs in the center instead of the side?
    I looked at a 200 at a local saturn dealer that was supposedly
    a '91, but the engine looked the same as the 10V one.  I thought
    '91's used the 20V engine.

5.  Given the choice between an '86 4000Q and an '86 5000 turbo
    (non Q), which would you prefer?  While I currently live
    in the SF bay area, I plan to move to the Sierra foothills
    in the next few years.

Any help would be appreciated!

-steve  (yeah, I've got the car habit bad) valin
'95 BMW 325i - '93 Audi 100CSQ - '90 Miata - '84 FIAT X1/9 - 
'71 FIAT 850 spider - '70 Lotus Europa S2 - '67 Matra D'jet - 
'60 Bugeye Sprite - '59 TVR Grantura MK1