Underneath thumping

Recently has some work done to improve oil pressure on the 2004 Dodge Intrepid. Since then have heard a thumping noise, seemingly under the car, when traveling over rough roads or bumps in the road. May be unrelated to the oil pressure work.

What is most likely to be the issue?

What kind of work did they do to improve your oil pressure? Sounds like it could be your exhaust system hitting something underneath.