lets cut to the chase, you don't know what you are doing or talking about so do not go an do any mods to your car, please do some research first and find out what you can and can't do. then choose what you want to do with your car.
Just stick to the intake and exhaust on your zetec, it isn't worth doing much more unless you have the money to do it all and do it correctly and want a contour zetec as a project car, hell it would be alot of fun with a well built engine and a tubro
basically there is nothing cheap that you can do to net you alot of power, so stop asking stupid questions about using things that you don't need to make power ...
edit: btw the people here are giving you good suggestions as to things you would do if you mod for alot of power, but they are not things that you need at the moment ...