I saw a GB for the drag 4 kit.

http://www.groupbuycenter.com/buy.aspx?id=8831

Would somebody tell me whats better in the Gen 4 kit? It seems like you get a Spearco intercooler, but iron instead of aluminum end tanks. And what's the difference between the 2 turbos? Also, do you have an option between the tubular and cast manifolds?