This car-stock. It’s rare (they only made about 2000 that year, and only the one series/year model had that engine. Only 20 or 21 were sold in my country).
You’d be better off to start with a 4cyl and modify it with engine swap etc.)
Convertibles aren’t the best for performance modding anyway- they lose some handling due to the structural changes, and the roof mechanism adds weight. For Audi that means start with a sedan (or wagon). BMW mods tend to start with coupe in 3 series.