Paying the difference for the slims isn't really needed since your using it in a vehicle...for example I did a set of slims on my motorcycle, but then again it came w/ a mess of wires, so I don't know if there was any real weight savings. The eliminators are needed so you don't get error messages on your OBC, so I'd get them. All of these are plug and play based on your headlight bulb style for whatever you order the HID's for since it will come w/ the appropriate bulb and the ballast will have the same harness style as whatever the bulb is that you're replacing...they're very easy to install. I'm going to forewarn your now though, don't put HID' into your headlights unless you have projectors (little crystal ball), otherwise the light is terribly diffused and you'll never get a good aim no matter what. They work fine in foglights though.

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