Transversus Abdominis Plane (TAP) block is a useful tool in pain management after abdominal surgery. It is a regional nerve block that targets T6-L1 thoracolumbar nerves running in the plane between internal oblique and transversus abdominis muscle. It is shown to help with post-operative pain management, reducing pain scores and narcotic pain medication use, as well as promoting earlier return to activity and recovery. TAP block became a very popular, safe, and effective therapeutic adjunct for many different abdominal surgeries ranging from obstetric procedures to general surgery procedures like colorectal surgery. Furthermore, it is used in plastic surgery procedures such as Deep Inferior Epigastric Perforator (DIEP) free flap or Transverse Rectus Abdominis Myocutaneous (TRAM) flap, as they involve extensive amount of abdominal soft tissue incision. Previous studies have shown that TAP block in these procedures significantly reduce post-op pain and narcotic pain medication use. More recently, Exparel (liposomal bupivacaine) has risen to spotlight for providing a longer, sustained local anesthesia. Various surgical disciplines have adopted this agent as part of their pain management protocol. However, there are no literatures that describe the effect of TAP block using Exparel for breast free flap population. The study hypothesize that delivering TAP block with Exparel (vs. plain bupivacaine) will provide longer regional blocking effect, hence aiding in pain control and recovery postoperatively. The investigators will be analyzing postop narcotic pain medication requirement and pain scores to look into this question.