In an existing kitchen, it is almost impossible to change the positions of the plumbing lines; and therefore you are ill-advised to tamper with the same. Such modifications have the potential to impact other apartments in the building, and thereby may compromise the entire structure’s functionality. Similarly, lighting systems too are more or less decided, with the wires concealed and plug-points and switchboards fitted! And these are usually well-planned and adequate; so unless absolutely imperative, it is better not to fiddle with it. Basically, try to use the entire setup without any major alterations and fitments.