pentastar engine question
 

i had a question i was hoping someone here would have some info on. the pentastar 3.6L is used in a lot of dodge/chrysler applications. I was curious why they have differents specs in different vihicles. example grand caravan and avenger 283hp 260lb-ft, and Challenger 305hp 268lb-ft. 22hp and 8lb-ft seems significant for the same motor. Is it a ecm change such as timing advance or something along the lines of exaust/intake, or a fuel delivery volume/pressure difference? just curious i appreciate anyones help or info