Why different thickness fins?, I'd like to see some fins over the core too, and not so much 'bulk' around the inlet. By having twin paths for the water you're making a low restriction block, but you're not gaining anything velocity, unless you make the two paths added the same diametre as the tube bore. what kinda pump are you aiming at?.
I think it's a good improvement on the other though. I like 'compact'
...
Are there any 'free' 3D modeling proggies out there?, that are'nt too large?(56K'er
)...