There cannot be wind without pressure so you don't have to add any additional pressure to the equation. Your body works in similar fashion. There is a moment when you have finished breathing when the inner and outer air pressure is equalized. Prolong this moment. Keep equalized without tension in throat.
Good respiration spreads work around all muscles.
On an Incentive Spirometer or Breath Builder, Bring ball to top smoothly and gently. Start with maximum resistance and as you reduce it prolong time you keep ball at top. Inhale fully to a comfortably full level. Maximal inhalation is used for emergency situations. Your body can lie.