I've replaced the incandescent headlight bulbs in both my bike and car with LEDs.
Key is having the emitters the same distance from the reflector as the factory bulb filament.
The high and low beam emitters should be staggered to provide good low and high beam performance.
Also key is having a flat top on the beam so as not to blind other drivers, yet have a long illuminated distance, or 'throw' in flashlight parlance.
This has been done by having a small shield on the low beam emitter.
Other designs
may have made this unnecessary.
The bulbs I have give me that.
They required no adjusting on my part, which is pretty amazing.
Installation is pretty straight forward.
The bulb is a direct fit for the intended vehicle, but there is a small black box for each headlight bulb that needs to be secured.
The bulb plugs into the black box and the black box plugs into the factory headlight harness.
My only complaint is they're 6500K which is slightly bluish, but very close to cars I've seen with factory LEDs, and they not be available domestically.
Vehicles with four-headlight arrays will need separate LEDs (bulbs) for high and low beams, of course.
I've also replaced car's my front turn signal bulbs with LEDs and all those of my bike's.
My car is older so there's no CANBUS worry.
But in many vehicles, this means the near no-load of LEDs compared to incans results in rapid or 'hyper-flashing.
Old school is to add a resistor to each LED bulb, a waste of time and energy.
I replaced my flasher relay with a solid stated version designed for LEDs.
The down side is when an LED bulb fails, I won't get the rapid flashing that warns me of a failure.
I routinely check that all lights work so that's not a big deal for me.
The US is way behind in vehicle headlight tech, and without LEDs (or the brush with HID) we're overdriving headlight at 35-40MPH — driving faster than is safer for the distance we can see.
Good street lighting helps to some degree, but vehicles need better lighting.
NOTE: Most of these bulbs, regardless of name or brand, are manufactured in China.
They tend to be sold in runs of thousands, then are OOS, sometimes never to appear again.
Or there are newer versions from more reputable manufacturers.
Also, LEDs aren't as simple to engineer and executed has various incans are, so there are premature failures from time to time.
That's a risk I assume but have yet to experience.
Regarding backup bulbs, another word of caution.
Everybody knows that LEDs are not nearly as hot as incan bulbs.
But the LEDs' built-in drivers can get very hot, so 'super bright' bulbs for tail lights and backup lights pose a possible heat problem, depending on the bulb.
Some users have suffered damage to the sockets because of poorly designed bulbs that are overdriven so as to be 'super bright'.
Discreet backup, turn signal, and brake light bulbs should be at little risk, considering their duty cycle and short use, but I've read complaints.
YLMV.