all i can say is, stick with the stock headers if you are planning on running stock heads or GT40's. i put the 1 5/8" Mac unequal shorties on, and i LOST a considerable amount of low end, but gained it on the upper end around 5200. Useless if you ask me for my somewhat stock motor. Those stock headers are not restrictive at all for what the application is used for. My opinion, Ford did it well with those headers for the application. Trust me i wasted my money. Yeah they look cool, but that is about it. As for long drops on a stock motor(E7's) we are talkling about something different cause of the design.
I have do disagree with you MiracleMax. On a stock or mildy stock motor, you need back pressure. Run straight long drops on a stock motor and i will run my stock headers with aftermarket exhaust on mine. i will produce a better "useable" torque curve than you. Dont ask me for equations, cause i dont have them!
