Whatever it tricks it is doing it at all rpm thus asking for more hpo at all rpm. So, now in the higher rpm it's asking for more volume of hpo, which the hpop is already having a hard time keeping up without the 18k mod. I have real world results, not theory on what happens when you have a 18k mod. Put a scanner on your truck without the mod and see what your hpo pressure is at wot, then do the same with the 18k mod. In lots of cases you would see better results with a 10k or 6k mod, all depending on what the condition of your hpop is.