well to put an end to it yes intercoolers add more hp they lower combustion temps, the whole purpose of the intercooler is to lower temp of the compressed air charge,,which in turn is a denser aircharger therefore the cooler denser air makes for a more compressed aircharge,,these trucks have more torque and more horsepower,,im in process of installing a larger intercooler off an 06 cummins with all tubes and intake snorkle,,the reasone why they changed to intercooler was overheating problem on 1st gens ppl like airco or banks give scientific numbers on how it work techically,, and yes ive seen dyno results on adding intercooler to your truck it does make more power,, at our shop we have installed lots of these upgrades to older trucks,,,ist gens are 88 to 93,,2nd are 94 to 98 1/2 3rd are 98 1/2 to 02 4th gens are common rail thx