The #'s are low because its on a mustang dyno. It took me 3 weekends because I pulled everything apart before the heads and cams got to me. Then I started the install of them the next, got it about half way back together and realized I needed different bolts so I had to wait another week to finish it. If I had had all the parts when I started I probly could have easily gotten it all done in 2 weekends. As far as the headers I have LT headers and I had to drop them before I could pull the heads. But I've heard that if you have the stock manifolds or shorty headers you can pull them out the top with the heads but thats just what I heard. Whether thats true or not I dont know.