It is still plastic, but seems to be made better. It's biggest benefit is having everything machine threaded, temp sensor, plug, and thermostat cap bolts. It's a HUGE improvement. I think the only aluminum one I have found would be from HTP, and they are quite pricey.
I will try and repost the pics, I think it was my bad on that one. There are only three, and not extremely detailed, basically before, off, and after..LOL I got to working, and forgot to take all the pics I should have.
2003 Pitch Black SVTF, K&N Drop in, CFM dog bone. 155,000 miles. **SOLD**
2001 Sentra SE 2.0 w/JWT Pop Charger 463,000 miles.