I replaced my original circuit from Jeff Beck strat, I changed lots of pickups, so I needed to buy new harness, made by professionals . Now guitar sounds better than before, but take care you have to add one more ground cable connecting the tremolo bridge at the back of guitar. Cable is missing in the set you receive, I used the cable from old harness.
Otherwise, everything is very well build, and is very easy to install, it fitted perfectly, no problem