Hi Pete,
With a 10-bit ADC that is typically used on the Arduino boards, you can only get 1024 voltage readings between 0 and 5V, giving a difference of 4.88mV between readings. Considering sensitivity of 45mV/kPa, the resolution is about 108Pa.
We do have some more sensitive differential/gauge pressure sensors, but I need more information on your application to recommend the most suitable device.
Regards,
Tomas
PS: If my answer solves your question, please mark it as "Correct" or “Helpful”. Thank you.