Hi,
I am using the H&R Springs part No - 29176-1 they are 30mm Lower than Standard,
They also offer a spring set 45-50mm lower for none gti but i think a gti is around 15mm lower as standard.
H&R sit lower than Sportline but are abit harder i would say, still fine but i am running 19'' CHs also on the Gti now,
Heres how it sits on H&R with 19'' CHs -
