Intrapleural Pressure during forceful expiration is
Intrapleural Pressure: (ITP) / Intrathoracic Pressure
It is the pressure within pleural space (space between visceral and parietal pleura)

At beginning of inspiration = -2.5 mm Hg / - 5 cm H2O
At end of inspiration = - 6.0 mm Hg / - 10 cm H2O
At end of expiration = - 2.5 mm Hg / - 5 cm H2O
Forceful inspiration = - 20 mm Hg
Forceful expiration = + 20 to  + 30 mm Hg
- 20 mm Hg
+ 5 mm Hg
- 5 mm Hg
+ 20 mm Hg