[Grandpa]

Originally Posted by Steve Depends on the amount of air being flowed.

Originally Posted by Steve That makes sense for a boosted car, not so much for N/A. On motor his car might be a little lazy until he hits the panic button.

Originally Posted by TrueStreetTim As we know; any engine will make its best overall power when treated as a complete system. Let me nerd out for a moment.... As engine speed increases, so does flow rate. As restrictions (collector, converter, muffler, bends etc) increase, velocity reduces power accordingly. Smaller diameter pipes flow less volume than larger ones, but the exhaust in the smaller pipe flows faster. Until you reach the RPM where the sheer volume of exhaust gases require bigger primary tubes. This is the basis for the OP's question. Essentially; Each header size creates a certain "torque boost". The size of the header determines at what RPM. If you plan to drive the car around all day at say, 3-4.5 RPM, a 1" 5/8 header is your man! Any bigger and you'll lose a noticeable amount of low end torque. 1" 7/8 header lives above 5k where most of you have your fun. Not to mention the Coyote's spin to the 7's. There is no reason not to go for the 1" 7/8 with the Coyote in our opinion....no matter the combo.

That's what I said. lol.