The LS1 only makes 25 more HP than the 5.3L. I don't know what you've got (4.3, 4.8, 5.3), but $6k could be used to make a lot more than 25 HP if you do have a 5.3. Now, of course, the LS1 does weigh a lot less than the 4.8, 5.3, or the 6.0 because the LS1 is all aluminum, and the others all have iron blocks. How well would an aluminum block hold up in a truck, doing truck type things?