Hi,
My brother-in-law used the Pagid Black as well on his 911 and had the same issue as Boxtaboy. Unfortunately, he ended up changing them back to new OEM pads because nothing he and his Porsche mechanic tried worked.
Personally, I use Mintex (red box) and they've been very effective. But, I guess it also depends on one's driving style. Are you planning on tracking your car??