Just saw your message, sorry for the delayed response.
I run a harness for my lows and highs even with the error code eliminators.
I also run a set from ddm in my cars low beams with NO harness.
the only reason guys run a harness is cause of the drls using the highbeam bulbs. It only sends 1/2 the voltage which screws the ballasts up and sometimes it doesn't fire or it does.
The relay is able to stay picked , and will remain picked up which is a smarter way to go.
Short answer, I Run a harness for lows & Highs, but not for fogs.
I am 100% satisfied with their products, I will keep ordering from them anytime I need something.
I know guys complain, but when it comes to these kind of products, of course you are going to have a few bad ones, its unfortunate, but its true.
Anything else Just ask!