I have been in touch with Eibach UK and they say their kit lowers the front 20mm and the rear 25mm
the GT 3.2 is already 10mm lower than a stock JTD.
when i had the Eibach springs fitted, the front was not lowered at all! it's now taken 12 months for it to finally 'sag' and settle at 10mm lower than original at the front. the rear dropped by around 25~30mm straight out of the box (haven't remeasured the rear again).
i think it is 'difficult' to drop the front of the V6 any more without breaching some local traffic authority rideheight requirements:
*some countries require the front indicators to be a certain minimum height from the ground: GT indicators are already mounted 'low' in the bumper
*many countries (incl australia) require a minimum clearance underneath of 100mm
with the Eibach's the clearance at the front 'looks' around 100mm as it is (i haven't had a ruler out yet). the bottom of the exhaust, and undertray sit very low.
i am still planning to lower the car another 20mm, but thinking carefully about what implications this has on ground clearance. i don't think it will be a major issue in terms of daily driving, driveways, etc. and it would be unlucky for my car to be inspected/checked for this (perhaps unlike the UK where you have frequent MOT requirements?).
i have KONI Sport dampers, and i am told by my mechanic he can perform a simple modification to re-seat the spring perch to a new 'lowered' position if i desire. that it is a relatively simple job of removing the original retaining C-clip around the damper, grinding a new slot for it, and pushing the perch down. i'll probably have this done on my next service when i'm having the Q2 diff fitted.
i didn't realise this was possible with the KONI Sport dampers, but it is now a bonus. not sure if it's applicable to other dampers (eg: KONI FSD? bilstein?). but i suppose if you went with a spring-damper combo, this may be another reason to choose KONI Sport.