i have been using this additive from ford and it seems to help out not sure if its cost effective or not as i got it for free.
2002 ext. cab lwb 4x4 7.3
05 front 08 rear conversion
4in lift,forged rod motor,tunes by tsd,bts trans,6.0 transcooler,6 autometers to watch,studs,springs,push rods,238cc hybrids,itp reg return,stealth hpop,tsd custom fuel system and sump,an so on
6.0's pay the bills and 6.4's soon..