i just installed a set of Z1 reworked injectors. Keep in mind for that price you need to make sure your old injectors are in spec (will ohm out properly) to get a full core charge, if not your looking at roughly $500 for them, which in my opinion are not worth it. I got my core back and i find these injectors so far are very good...i would not rely on them to last me forever but its a good holdover for me until i get a chance to upgrade the fuel rails too. When they rebuild it, they are basically cleaning them out, changing out the lil filter and the cap and making sure they all ohm within spec. Thats what rework basically means.