They do give more horse power
yes
They help the engine "breath" better.
If your looking for raw open power than no. But you can't drive a vehicle on the roads with open headers. So it's mainly off-road trucks or high hp mud trucks that run open headers.
Headers help to maximize exhaust flow which allows your engine to run more smoothly and use less power per stroke. Because of this headers can improve fuel economy but the change is very small.
intake manifold and headers or replace with 350
Installing a after-market exhaust will Increase MPG and low-end and high-end power outputs. Also with addition to headers will come Increased loudness and Horsepower and low-end torque.
The only company to sell headers made for this car is a company called Ford Power Train. Very high quality headers that are built very well. Just google the name and you will find there site.
I added: Hypertech chip, K&N air filter, headers with dual exhaust. The best improvement came from the headers.
A fan on the engine blows air through hoses and into the heater box that is wrapped around the exhaust headers. The heated air from the exhaust headers in the heater box is then blown into the cabin.
find the power wire at the fan if theres power to it then the fan is bad
headers, flowmaster, k&n, underdrive pulleys, cooler thermostat, hotter coil, electric cooling fan, advance timing