I think the radiator cap will burst before a freeze plug, right? Is' that suppose to be the first place of pressure release?
And the HO pump is just a larger dia impeller I think, which helps the flow more then increase pressure, the better the flow, the less pressure you have, they are an inverse of eachother. I am almost certain too that it is a 37 gpm pump instead of a high 20's gpm.
I also know there is a second revision offered. When I purchased my new 05 Pen motor, I came with an extra water pump that was a little beefier then my 1998 hi-flo pump. I put then on the truck and it seems to always stay cool, I have pulled 12k and had no overheating issues at all.
1998 Extended Cab Short Bed 4X4
Current Mods:
BRAND NEW 2005 PENINSULAR SHORT BLOCK, 2005 AMG Block, 18:1 Custom pistons,3 1/2" stainless custom exhaust, 3 bar MAP
EGT, Boost and Tranny Gauge, 24"X12"X4" Custom Intercooler (Had to notch frame)
Holset HX35 Turbo (24-26 psi) With Custom 3" DownPipe
TransGo HD2 Reprogram and Shift Kit