hello i have a 99 nbs silverado 1/2 ton with a stock lq4 6.0l (iron head with a 2001 6.0l reman crank to mate to 4l60e trans) out of a 2000 3/4ton silverado. i have been searching for supercharger kits that would bolt / program with the truck. i used hptuning software to swap over stock engine calibrations for a 2000 3/4ton 6.0 silverado into my pcm and also switched to electric fan controled through pcm. im running the original pcm. all the kits i have found are for 03 and later. i know that in 03/04 the engines (v8) in the trucks went from dbc to dbw and have different pcms (increased memory and better maps). i also know that to convert my 6.0l to an 03 equillavent would intale heads, cam, injectors, fuel system conversion, intake/throttle body, TAC module, pedals, and harness. i have read that you can install a later OS into my pcm is that true? or would it be better to just get an 03 pcm and program it to my vin? if pcm replacement what sort of complications could i run into (taking it to dealer, sending pcm out, pcm connector changes, etc)? i have been chasing my tail on and off for a year doing research on this and other mods but it seems like 99-03 silverados are a pita to do mods. any advice, guidance, ideas, anything would be greatly apperciated. also the area i live in there is no dyno's/tuners near me.