Lowering Springs Audi A6 4B 2.5 TDI Suspension

Hello to all diesel drivers and enthusiasts!

As previously mentioned, I now have a fantastic A6 Avant 2.5 TDI, which will undergo a couple of minor modifications.

First, the chassis:
At Audi, I was told that neither the sport suspension nor the S-line suspension can be retrofitted, as various other parts, including the spring-damper unit (i.e., the shock absorber) and, in the case of the S-line, even components like the control arms, are different. I was recommended *** suspensions, but I wasn't given any specific expertise on them, nor was I provided with a price for installation (which, given the time and opportunity, I believe a DIY enthusiast like myself could potentially manage!). However, I was eventually given the information that the hourly rate is €98.20 plus tax.

I was browsing online and found a suspension kit from TuningConcept (coilover) for around €700, but it offers a significant lowering of 45mm (up to 75mm). Ideally, I'd like a more moderate lowering of 20-25mm in the rear and 25-35mm in the front, not extremely low (otherwise, I won't be able to get into my underground garage!). Does anyone have any relevant experiences or a good recommendation for a (tuning) workshop in the Greater Hannover area? I'm looking forward to your replies...

Regards,

Holger.