I have a set in a mid-'90s American Standard strat. Made a huge difference. It actually sounds like a strat.
I had a conversation with a Fender rep when the new American series came out. He said Fender was heading back towards a more original Fender sound. For a long time they had been voicing their pickups towards a more neutral sound, to let people get a more modern sound. With the new stuff, they are heading back to more traditional strat sounds. So it kind of depends on what model you already have. I found the biggest improvements in positions 2, 4, and the bridge only. They do have a bit less output than the standard pickups, though. I had to raise them a little higher.