No they're not, trust me.

I used it for 6 months and took it out and it's not any brighter with or without the harness.

The only place they help the most is when using high-amperage lamps to help carry the higher amperage more efficiently. Any low-amperage light like mine won't be very phased.

It's about as much of an "upgrade" for stock headlamps and low amperage headlamps as the four-port injector "upgrade" is for the 4.0L engine. Placebo effect.

 

Can somone explain why changing the harness will have a impact on the headlamps brightness?

 

Better wiring = better current flow

 

Because the factory harness restricts amperage flow.

The aftermarket harness attaches directly to the battery.

The harness will give you brighter results with high amperage lights. But if you're using low amperage lights, like my TruckLite LEDs, you'll experience no difference because the factory wiring is more than capable of providing low amperage.

I didn't even see much of a change with factory sealed beams. Maybe if you upgrade to H4 halogens you'll see a difference.

 

Instead of the 12v for the headlights going through the headlight switch and a whole bunch of thin wire, the 12v now comes directly from the battery which is triggered by a relay controlled by the headlight switch.

 

Think of power like water the faster it can move from point A to point B the better.

 

I gotcha. At least until I have low wattage LED's in there. I just ordered them, so I'll wait for the install. I'll make sure to grab some before and after pics.
Maybe it can be the start of my build thread. lol