Im researching doing this mod, however in my search results on the 'bay, a fuel pump relay comes up in the results too.

Do I need this item?

Thanks in advance,
dx4

Yes and no.

I've not looked at the ZXR400 fuel set up but the relay is probably used to turn the fuel pump on / off with the bike.

Depending on how your wiring this up (and to what) you may / may not need it.

If it were me i'd get it and wire it up the same as the Kwak setup.