Not sure if right place but couple of questions.

The 5.3 from 2003 was rated at 285hp,325tq in Silverados. In 2004 it was rated at 295hp/335tq if i read right. What was changed to cause this difference. The reason Im asking is because im swaping the 5.3 out of my 04 with one from 03. Since i will be using the 04 computer will I need to do a crank relearn?

The crank relearn is pretty hit or miss. Sometimes people need to do it with a new computer/tune, sometimes they don't.


The extra 10hp won't make much of a difference, shouldn't be any differences in the motor. I THINK the added hp was from an intake change (from cable to wire), since you're probably using your original intake, your computer shouldn't notice a difference. I know the HO 5.3's use the 4.8 pistons, and have a higher compression, that would need some tuning to take full advantage of, but I don't think the HO came out til 06 or later.