I've sat in my friends' 3rd gen Tacoma and there's like a 1' between my head and the headliner. Meanwhile in my 4th gen I am constantly grazing my head along the headliner.
The 4th gen has really good seat adjustment but if I sit too low and far back I impair my ability to see over the hood directly in front of the vehicle. It seems like removing the headliner would be the best option but I've chosen to just live with it.
Maybe we can start a support group for tall 4th gen owners!