Originally Posted by drostedrummer89
That's true, but he doesn't even have an aftermarket intake. which means that any other mods he does are going to suffer since he's not getting optimal airflow in. And running a lean code.
This isn't true. FocusSport made ~175whp on their project zetec years ago with a stock airbox and cai didn't do that much. The difference between a CAI and a k&n drop in filter will be pretty minimal on our car honestly. If you're on a budget stick with the stock airbox, or buy an SVT airbox and use a k&n filter. I would much rather use that than an ebay cai of questionable quality. You're going to be limited by the size of the MAF with any intake anyways, you can't change that without custom tuning.
Instead of doing more performance mods to your car, you should make it lighter. Power:weight ratio is where it's at. Deleting parts from your car is free! You would be surprised by how much of a difference a smaller/lighter wheel and tire combination will make. My car with just the rear seats removed is noticeable.