I have found that great pinch harmonics come from technique, then the guitar and pickups. I can get better and stronger pinch harmonics from my stock PRS McCarty compared to my LP no matter what pickups.
I agree with papersoul i think its more about technique and the type of pick you use and how much gain you use. Hi output makes the signal stronger thus making harmonics easier to pull of.
If you are after crazy harmonics I would recomend these pickups, Invader, JB, Bill Lawrence XL-500. I would personally pick the xl-500 over the other two because it is alot more versitle. Even more so than the JB.