Yeah for 2001 & up, the power went from 345 HP / 350 TQ to 350 HP / 375 TQ with the 6 speed manual, it went to 350 HP / 360 TQ with the automatic. The HP gain is more than claimed because that LS6 intake manifold alone is worth at least 10+ HP & GM made the cam slightly larger as well. I think they did a few other minor things for power as well. I'd have to look it up again though, it's been a while since I read about it. As said before, any year C5 is good though.
I bought it with 15k miles, it just rolled over 40k. I changed the tires and did several oil changes and changed the brake pads. Nothing else beside that, however i am going to take it to get all the fluid changed soon.
I found a 2002 vette with about 68k miles hoping to trade in my current car to get it, I don't need a new car, but I sure would have a ton more fun in one.
Spend another 3/4 k and you can find one with half the miles. You should be able to find a decent 2000+ vettes for 17k with around 50-60k miles. Join corvetteforum(.)com, that should also help with your search.