The D16Z6 with give you less grief. The D15B requires a PO8 ECU and some of the coolant lines need to be moved around. Also make sure you are getting the 130HP SOHC VTEC and not the Civic ETI's 100HP (give or take a couple HP) SOHC VTEC-E (which requires eve more changes to work exactly right). There are also two 130HP versions of the D15B. One of them carries the rare 3 stage VTEC valvetrain.