My personal go to would be the Bilstein B12 Pro kit, which comes with Bilstein B8 shocks and Eibach Pro springs. On the standard Sport suspension it would give you a small drop on fronts and rears.
A3 Sport - 26.5"
B12 - 25.5"
In terms of ride harshness it won't be much different to Sport suspension but it would be a lot comfortable with improved handling.
B12 is slightly expensive kit and you can go with only Eibach Pro springs to improve things slightly which would be slightly less expensive option.
Apart from B12 there are other slightly less expensive options available as well, which I am sure others will be able to contribute.
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