The filter provided with the DW Civic kits is designed to fit the US Civic Si and not the FN2. It is a slightly different shape and will not fit properly into the FN2 fuel cage. If you use it you will have fuel issues.
Use the "sock" filter from the OEM pump and it will fit perfectly. Give it a good spray/clean with degreaser or brake cleaner and it should look like brand new.
I gotta ask because i've always wondered. Can you just change the the fuel pump to say DW65C without any ecu/fuel pressure mods? Or what is needed? Im thinking of going for fuel pump and injectors with bolt ons on E85 and with headroom to spare for possible bigger upgrades.