Finally, youíll need the Bentley Repair manuals for both the Coupe Quattro and the 200.  Cory says itís amazing how different the electrical sections are, but they complement each other.

NON-FACTORY PARTS:

High performance cat:    Get at any racing shop.  I paid $80 for the largest 2-way unit w/2.5" openings at Summit Racing.  Not stainless.  Good up to "460 cubic inches," they told me. Should suffice for my 132 forced induction cubes.

Stabilant 22- You're-doing so many connectors, give yourself every chance to avoid bad contacts.

Boost Gauge:  I used a stock looking VDO 0-30 lb. gauge, replacing the voltmeter on the lower console.  Another option would be to buy an aftermarket shell and mount it on the A pillar.  Install with a "T" in the green boost line that runs to the computer.

Hood
Many parts are carried over from your CQ hood.  The hinges, hood strut,
window washers (with heaters), underhood pad, latch bayonets, small
fasteners and other items I'm likely forgetting are common to both
hoods.

Like anything else, however, the "thoroughness" of your hood conversion
is driven by budget.  Using the above referenced part numbers, and
crossover parts from the stock CQ hood, you can do a full factory
conversion which would be indistinguishable from something Audi built.
I'd guess this would cost about $2K depending on the cost of the
paintwork, how much labor you do yourself, and not including headlights.

Another alternative, though, pursued successfully by others on the 20v
list, is a "budget" conversion which uses only the new hood and grill.
If you were lucky enough to find a salvage '93-'95 Audi 90 hood in the
same paint color  as your 20v, you could conceivably do the project for
the bare cost of the hood and grill.  This approach leaves the stock CQ
three piece "hood latch carrier" assembly in place.  This approach
reportedly works fine in terms of mating up the latch bayonets from the
hood.  However, the safety catch mechanism will not line up.  What
others have done is to simply remove the safety catch, and do without
it.   This approach also reduces the project labor considerably, since
replacing the hood latch carriers is the most time consuming part of the
job.

The other main decision to make is headlights. (the stock CQ headlights
reportedly will work, in the sense of they don't interfere, although
they don't match up perfectly)   The cheapest (non-stock) alternative
would be to use V6 90 or cabriolet headlights purchased used.  At the
other end of the spectrum would be RS2 or late S2 H1/H1 projector beams.
Be aware that these euro lights do not have an integrated turn signal
lens.  This is fine if you are replacing the bumper cover with an S2 or
RS2 unit, but if you are sticking with the stock bumper, you will need
another turn signal solution with the euro lights.

In summary, this is not a difficult conversion.  Be careful when you
bolt up the new hood, the hinge bolts float to give you multi-plane
adjustability, and it is possible to close the hood such that it hits
one of the fender edges.

The B4 hood conversion really updates the look of the 20v 90.   In the
case of the CQ, it now looks like nothing else sold in the US.  It's not
a cheap proposition, but will be worth it for those of us who want to
make a special car even more unique.