I have a 2005 f-250 6.0 that I just recently bulletproofed. It had these same performance issues before & after being bulletproofed. I guess I should back up & say it was a repossession & I only drove it 2 miles before bulletproofing it so I don't know much about the history. The truck has ARP head studs, oem head gaskets, blue spring upgrade, upgraded oem oil cooler, EGR delete, & is straight piped out to duals (done before I bought the truck). New ficm just installed & reading 48.5 volts. NOW for the issues...truck runs & idles perfectly, however, it struggles to accelerate in the mornings (or whenever the engine isn't up to normal operating temp). I will be going up hill & it will have to downshift & the rpm's will be around 3k but speed is not increasing, sometimes it even drops. AFTER the engine reaches normal operating temp, this issue goes away & I'm still left with the issue of low/no turbo pressure. I usually don't get above 5psi of boost unless I have it floored & I'm doing around 65mph, then it takes off like a rocket ship...topping out around 20psi boost.