/t/ → /p/
The plosive alveolar /t/ becomes a plosive bilabial /p/ when it’s followed by a bilabial sound, such as /p/, /b/ or /m/, because of assimilation. The change only affects the place of articulation, but the manner of articulation (plosive) and the voicing (voiceless) remain the same.
/t/ (followed by /p/, /b/ or /m/) becomes /p/
That person. ǀ ðæp ˈpɜːsən ǀ
It boils. ǀ ɪp ˈbɔɪlz ǀ
That money. ǀ ðæp ˈmʌni ǀ
And here are some examples taken from real life:
But, yeah, at that point I thought, “My God, I could be much more charming than Hugh!” (Rupert Everett, BBC4).
There were sources that believed that they had a hand in Philip’s assassination (Paul Cartledge, BBC4).
So, clearly, in a way, not much of a regular rythm there (Michael Rosen, OpenLearn)
This is the type of work I do with my students in my one-to-one classes. I make them practise these processes with exercises until they improve their comprehension of native speakers and are capable of speaking like that themselves. If you are interested in my classes, you can contact me here.