I don’t know when this occurred but one of these drop links has fallen off my AW11 front sway bar.  I discovered this on a friends hoist when trying to find a bad clunking noise when driving over pot holes.
It's possible it may have been missing before I bought the car as I have not noticed any change in how the car handles.
 
I also don’t know how the car will handle after I replace this missing link as with only one link attached the sway bar is not doing anything to the front suspension at all.
I should add the vehicle is also fitted with D2 coil overs so these maybe making up for the front sway bar being out of action.
 
Having not seen a AW11 drop link before I am thinking that these ones are modified to allow for different lengths.  Is this normal on a stock AW11?
The current length of this rod between centres is  18.5 cm.
 
Question:  Am I going to gain better handling if I replace this drop link.  The suspension is very hard at present and to me the car handles well.
 
Does any one have such a link rod they would like to sell?

When you say the suspension is hard - do you mean the ride is hard, or the suspension is stiff and not easy to compress?  Fitting the missing swaybar link will stiffen the front end even more, and MAY cause understeer.
 
And yes, your supposition is correct, the stndard part is a fixed length, this is modified.  TwosRUs do replacements.

Yes the suspension is stiff and very hard to compress to the point where if I am outside pushing down on a front guard with both hands there appears to be no give and I worry I might bend a guard.
The ride for me is not hard, feels very nice on the road. My only complaint is this loud clunking noise I hear over small pot holes.  Noise seems to be RH side some where near me feet.  Maybe the pillow ball on top of the RH strut. 
I have had a look around the camber top but don't see any sign that anything is moving.
 
Only other thing that I can add is if I jack up under the RH side of the front cross member until the RH wheel is off the ground the LH wheel soon follows it.  I imagine this is intentional as the car was set up for circuit racing (RobYob's old door stop)
 
 

A clunk in the suspension could be from a number of locations.  One that often gets overlooked is the steering rack mount bushes.  With a stiffer suspension setup everything works hard, and tends to wear faster.  When were all the bushes last checked?

That's a good question and one that I will look into.  Thanks.
 
Do you know what the measurement center to center is on a standard front sway bar drop link?

235mm centre to centre, 

Thanks again Dennis.
 
This link kit looks good.  Will cater for many lengths.
http://www.ebay.com/itm/ADJUSTABLE-SWAY-BAR-LINKS-FOR-AUDI-A3-8P-2003-2013-FWD-/281167566809
 
Will buy this unless anyone has a seen some thing better.
Could buy more units for anyone interested to bring shipping cost down.