I've done a couple H&S DF kits thus far and have some info that may be helpful if you didn't know it already.
Check the pulley clearance on the bottom and inside of the pulley before you fire the truck up. The bolt used with the spacer threaded into the location of the secondary water pump mount may need to be replaced with a hex head style bolt that is not supplied with the kit. Note: Do not tighten the pulley down until the very end just before the belt goes on.
Also, when you mount the pump to the bracket, thread the high pressure line on the pump just before you mount the assembly on the truck for final reassembly. Make sure you already have the fitting in the rail already in and capped off so you minimize the fuel system exposure.
When you have the assembly mounted with all of the mounting bolts threaded in, hold the pump and gently move the assembly up and towards the drivers side as much as you can, then tighten it up. It's only a small amount, but I found it makes a big difference in clearance. Make sure the mounting bolts are tight (I torque to 24 ft/lbs), otherwise the pulley may contact the secondary water pump after some time on the truck from the belt load.
Good luck!
