You might find the ECP springs will make the car sit funny if its got the sport suspension on it already (which being a quattro it might well do)
I know most aftermarket spring manufacturers dont generally provide springs for cars with any kind of factory lowering options. My brother had a hard time with his E30 BMW because of this. He had a 318iS which is fitted with BMW's sport suspension from the factory, which lowers it a small amount and adds bilstein dampers. He baught a rear spring from the factors for a 318iS but it was about an inch higher than the old one, and made the car sit all cocklegged. Factors said that was all that was listed in their book and that they dont do springs for factory lowering options, even though ALL 318iS's are lowered from the factory...
If you dont want to lower it at all then i guess its the only option, so give it a try and report back on what you find!