I got a JS1000 the other day and it had a Fred pickup with "Dimarzio" stamped on the bottom right corner of it. The pickup sounded shrill to me and reminded me of why I sold off the Fred I bought years ago for a 540R I had. This time, before giving up on it, I turned it around so that the Dimarzio label was upside down in the top left corner. Doing this added some meat to the sound of the pickup and I'm going to keep it. Interestingly, this same 'turning around' thing worked to fatten up a Evolution bridge
I was trying out in another guitar.
The way the Dimarzios are built, it appears that the output wire of the pickup should most logically be closest to the hole that connects the pickup route to the control cavity. The way 'Dimarzio' was written on the Fred pickup makes this seem even more logical. This setup is shown in the top image below. Turning the pup around gives you the bottom image below. The bottom image is what made my Fred come to life. For both the Fred and the Evolution, turning it around also put the 'hot' coil of the pickup closer to the bridge instead of closer to the neck. Close to the bridge is where a split humbucker typically (based on my gibsons) has its live coil.
There is definitely a difference between the two for my ears. Try turning before dumping your pickups and you might find that you like them after all.