That is what I am saying. It is restricting. All you have to do is your exaust and intake manifold. I could have cut so much off that it would have broke in half, but stoped when I felt structural integrity may be a problem. Do not even have to monkey around with the head. Shoot if you just grinded off the crummy weld stuff you would have done something. Ya, I need to get around to my exuast. Did you notice any difference?