A friend of mine has a 2003 Hemi Ram 5.7 that has 345 hp and 345 tq. I just bought a 2008 Ram 5.7 that is 345/375.
I was curious what makes the 2008 have more torque and same power.

As the 5.7 evolved it got electrically controlled variable length intakes and variable valve timing. Both boosted low and mid range torque. I don't know the exact years that they came in... but I'm on my 4'th gen III hemi. The first early version ran great but needed to spin (downshift) to make power. The later versions have a lot more usable torque at moderate revs. The 2006 I had did not have these goodies. The 2011 did. The 8 speed (2015?) helps even more to increase usable power and smoothness.

I think the specs for the '03 are off. The 03-08 Hemi's are all exactly the same. 09 is when all the extras came in (VVT, Eagle heads, etc)