Well yeah heavy work will literall thicken the abs, just like any other muscle, the muscle fibres thicken up and make the muscle bigger. It wont happen overnight though, b fold the truth has super thick abs and they have come from years and years of work. You could try to heavier ab stuff and when you start noticing a differance see what you think to it, if they start getting too thick well then just back off all/some of the ab work...
only real way to find out is to try it for yourself
only real way to find out is to try it for yourself