I'm going to go against the grain here (that's nothing new) and recommend you fix the problems before you drive it anymore. For a baseline, understand that you have TWO known problems. That engine is too good looking to accept what you describe as very poor performance. If you had a bad exhaust leak from the get-go, you very probably also have a vacuum leak. Same gasket, same clamping.
I know you're very fond of the method you used for installing the manifolds, but I think it's the source of your problem and will continue to be. If you look back to
Our previous discussion you'll remember what I'm talking about.
look at the picture at the bottom of page 95 in Leo Santucci's book you'll see that he also uses the studs. I think he copied my idea. Ha,Ha.
The felpro gaskets I was referring to are #1257-int, #1448-exh. Do not use them.
I've been wanting to ask you this question for weeks. Did you put that engine in the truck with the headers on it and the front sheetmetal on the truck?? I can't shake this nightmarish vision of sliding that thing in there with the waterpump pointing straight up in the air and the headers pointing straight down.
