A "thump" is heard/felt when I turn the steering wheel fully and left and right.

With the engine running and car stationary I turn the wheel and feel a slight thump through the wheel. This happens occasionally if I turn the wheel past 180 about degrees. All other aspects of the steering system seem to operate normally.
I would appreciate some advice on this

 

You need to do a little more testing.
Put hands on top of shock/strut tower (engine bay) and feel for thump when someone turns the steering wheel
If you can feel it is coming from there then need to check struts out.
You can also listen to the steering and see if it is coming from the rack and pinion.
My guess, I am not there to see, would be the ball joints or outer tie rod ends are loose.
Jack up front wheels and hand at 12 and 6 check for play.
The hands at 9 and 3 check for play.
And check the sway bar links

Good luck