I'm new so I don't know the exact protocol, but I tried a set of the Callaham standards in my American Standard Strat. They were very nice pickups, but I replaced them with Novak's. They just sound better to my ear.
As far as cryo goes, I was awake durring enough of Engineering Physics to understand the theory, but it would seem the amount of any improvement would be negligible.
Some years ago it was fashionable in high power rifle competition to cryo barrels. All maner of improvements were claimed, but over time experience showed little, if any, improvements in barrel life, machining properties, or accuracy. I think only a few custom makers use it anymore; for what it's worth.