I talked to Matt at Spartan about the lag and he explained that it is built in to the factory programming because of the DPF. When does a 7.3 or 6.0 smoke the most? Initial take off right. So to keep the DPF from getting clogged all the time they defuel the engine on initial take off. The harder you mash the pedal the longer the delay. Sucks and if you dont account for it you could get yourself killed. Anyway, once you remove the DPF the programming can be adjusted to remove the delay or lag. Its not actual turbo lag, the turbo's spool very quick but not until they are supposed to according to the programming.