Ok,well this is my theory...when I bought my golf it had crappy purple dump valve on which I thought needed replacing,so I did with a forge with a green spring.however around this time my car started flat spotting at full boost when driven hard.I am now wondering wehter the car has had a remap in the past and reuqires the yellow spring?thought I'd just buy one and try it?thing is I have no idea what a standard and non standard 1.8t is supposed to drive like.lol.