They help the engine "breath" better.
10 to 20 percent
Headers may add 3-5 hp depending on design and a cold air intake will add around 4-7 hp for a total gain of 7-12 hp untuned. Definitely worth it especially with the nice throaty sound you will get out of it.
240-260 horse power stock, supercharged. Buy a smaller pulley for supercharger add 30-60 horse power more.
about 100 horse.
if you can find the hp. of the eng., you can add between 12-20 more hp. for the headers.
Start with a cold air intake, then add headers. If you want 100 or more horsepower instantly add nitrous
a cheap way to add a couple horse is to add a later style escort intake to yours, say a 96-99 if the bolt patter is the same
yes
Clean out the carb and add a high flow air filter
When a supercharger is correctly installed, setup and tuned on a dyno it can add over 150 horsepower to a V-8. It can add more with other modifications to the motor.
20-25 as a rule of thumb. More with good heads.
ur cheapest way to increase horse power would be replacing your air filter with a cold air intake. you can also add a perfomance chip to your ecu.