well i dont have the def file for tunercat that will work with the 03-05 trucks, i have 96-97 trucks and 01-02 trucks so i cant go in and just modify my stock program, and since i want to get a tune from NP i dont want to drop the 80 bucks to buy the def file to change my stock program, because once i get the NP tune i will no longer be able to make any changes to my PCm because it will be locked. Basically just trying to save 80 bucks.