i'm assuming i can as the passenger side burns out first from what i've heard. do i have to buy them as a pair or can i use a used 1 from classifieds and just plug and play? thanks

 

4th gens don't have HID's unless modified by its owner.
Don't know of any reason why the passenger side would always fail first? That makes no sense. You've got to figure out what kelvin rating the bulb is and find its match. Replacing both at the same time would give you a better match.

 

Like previously stated would probably be good if it's the same type of bulb esthetically but otherwise as long as the ballasts are good you can replace just one bulb yes.

 

From what I've read at places like TRS and the forum that they work around, don't expect the bulbs to match output or color, even if they are the identical part. Bulbs put out less as they get used up and older. Color also changes too.

I resemble that remark!

I hope this helps!

 

It's preferable to change them in pairs since HID bulbs colour shift up, meaning they become blue>purple over time but this depends on how many hours the remaining bulb has on it.

 

Always change HID bulbs in pairs. Keep the good one as a emergency spare.

 

well, i just bought a single bulb cause it was $13.00 and i really don't care cause i'm thinking about changing the whole set up at this point. i'm sure at 5 years plus on the set up it'll look a tad different, but it already did so who cares.

 

You'll care when your headlight temperatures don't match lol