i have been using them for several years and have bee having good luck. my only gripe was the first run of them had a fitment issue with the metal swing latch for the injectors so i took the metal clips off of the original harness and used them, since then they have improved!
also the nice thing is that you can save your old harness' and break it down to make your own glow plug test harness! you will also end up with 4 extra injector/ ipr connectors that can also be used for a pigtail for 6.0 vgt soleniod!