So what have you checked then?
Wheel bearings
Track rod ends
steering rack? mounted securely?
Lower balljoints
Wishbone bushes
cv joints
Bent wishbone wouldent really cause a knock, would just affect direction of travel/tyre wear, i read you also had wheel alignment done, if it was 4 wheel then it would have picked it up.
Arb maybe depending how low it is.Droplink isnt likely on the one that fixes to the wishbone as the bush would have to compleatly shot, knocking is more common on balljoint droplinks when they wear down. Have you checked obvious things, loose bolts, wheel bolts, pads are secure, caliper is secure, no play in silders?
Engine mounts? R/H l/H dogbone mount, a bolt snapped where my dogbone mount goes into the gearbox yestoday and was knocking like mad.
You fitted coilovers, are they securely fixed, into the hub and on the tourrets? Spring secure/fitted correctly?
Basically someone with an ounce of knowledge needs to look over the front suspension, could sit here all night saying this and that but without the car here, i couldent say.