As far as the max safe pyro reading, it depends on where they put the sensor. I put mine in the drivers side exhaust manifold (pre-turbo). If you crawl under the driver's side of the truck, it's at the rear of the manifold...this is the most common place to do it pre-turbo because it's easily accesible. Around 1350 seems to be the general consensus on the Powerstroke forums, though I back out about 1250. Pre-turbo is most accurate, though some people are concerned about the possibility of the thermocouple probe breaking and going through the turbo.
The other possibility is on the downpipe (post-turbo). This has the disadvantage that there's always a difference between the true temperature at the turbo versus the post-turbo reading, and this difference can vary. The post-turbo reading might be 200 degrees cooler than actual under certain loading conditions, but 350 degrees cooler than actual under other conditions (those numbers are just an example, I don't know what real differences are--I guess it depends on how free-flowing the intake and exhaust systems are).
