How low would you class low speed? I've got a similar sort of knock from what I can gather from your description, mine can be there anywhere up to 40ish. Been chasing it for a while now, changed the top mounts/strut/springs, droplinks, wishbones, and will be changing the arb bushes next weekend as long as I get them sometime this week. 
Although, reading your post again, if it's "pinging", I'd be inclined to think top mounts, but I'm not a professional like Dum-Dum, so i could be wrong.
Although, reading your post again, if it's "pinging", I'd be inclined to think top mounts, but I'm not a professional like Dum-Dum, so i could be wrong.
![[Image: P1060836_zpsz3xgxt7q.jpg]](http://i1101.photobucket.com/albums/g427/wingnutz2/P1060836_zpsz3xgxt7q.jpg)