H&R is the brand which usually offers the greatest drops. These lowering springs go up to 70mm on some models. See the application list for exact numbers.
Lowerings over 30mm are usually recommened to be paired with shorter shocks like the Bilstein B8 which is also available from us. Drops up to 30mm are usually ok with original shocks in decent condition.
Lowering rates are calculated by H&R with a sample car. Things like battery weight, aircon model and engine differences will affect the actual lowering a little bit. If your car has an OE sport package like the Audi S-line or BMW M-sport which are lower than stock, then the actual lowering rate is less. Lowering rates are calculated from the base model height.