They are heavy, whether you notice or not is another matter. They're a great value upgrade. On track they will get out of their depth at some point. I never had any issues at all at 340hp with road use. Decent pads and fluid are a must. If I didn't use mine for track days I'd probably still be using them.
I offset the weight gain by fitting S3 arms which are half the weight of the steel oe. They add a little more castor angle and the S3 bushing supplied is stiffer than oe golf. Add a WALK kit and it's a great addition.