Many people are after the early Van Halen tone. So they get on a never ending quest of buying different pickups to get it. There are some aftermarket pickups out there that get close. But people forget two little things when they install it:
1) Angle the humbucker like Van Halen did. I know some people say it really doesn't matter how the strings are lined up. I disagree. How the poles line up or don't line up with the strings does make a difference, not a huge difference. BUT my ears do detect a slight difference. Find a photo of how his strings and poles line up and copy it.
2) No tone pots. Having no tone pots does sound different from when you load the pickup with a tone pot. Without tone pots the pickup sounds louder and brighter. Early VH connected his pickups to one volume knob. That's it. Disconnect those TONE pots or throw them away.
These are just two little tweaks that will get you closer the that early Van Halen tone.