I am trying to raise the horse power in my 2002 ford focus se and were wondering some options i could go with to boost the hp without having to spend all that much money. I am willing to hear all ideas even if they are a little expensive. I also am getting a K&N typhoon cold air intake and was wondering which one would be the best to get. Thanks!
The most cost effective option is going to be a Jackson Racing Supercharger. You read about it her http://www.caranddriver.com/buying_guide/ford/focus/jackson_racing_supercharged_focus_zx3_specialty_file
Expect to spend around $3500 for the kit plus another grand or so for the installation and dyno tuning. Also if your Focus is an automatic, there is a good chance that the added power of the blower will kill the transmisson sooner rather than later. As for various CAI’s and performance exhausts. The gains will be minimal you might see a 5-10 peak HP increase, but also with a corresponding decrease in low end grunt. If your after speed, you picked the wrong car.
My recommemdation is NOT not do this. It will result in all sorts of other problems, and short engine life. I would trade the car in on something more powerful, if that is what you want.
Superchargers for retrofit have been on sale since the 50s (McCulloch), and I’ve never met anyone who did not have some form of problem. The factory fitted have the engine beefed up to take the extra load put on it.
As the sayings go! “If ya wanna play! Ya gotta pay!” “If ya wanna go! Lay out the dough!”
Tester
Buying a Mustang is the easy way to double your power.
I have has zero problems with the Kenne Bell supercharger on my Mustang. It’s been on for about 35k miles now. Easily the best modification I’ve done to any car.
You’d be much better off spending any money on another car. I’ve had two Foci, both a dohc 2.0 and a spi, and they were both absolute dogs. You’d have to invest thousands into it to get any appreciable gain in power.
As others have noted, these mods would put other stress on parts that weren’t designed for it, causing premature failure and/or the the need to upgrade even further.
Buy a Mustang G.T. 
Guys, if he could afford the Mustang he wouldn’t be trying to boost the HP on the Focus!
With respect to FoDaddy, I too recommend against the supercharger if you’re doing this on a tight budget. First of all, a supechearger increases cylinder pressures to where reprogramming of the ECU and premium fuel are required to compensate for the increased tendency toward preignition. The other problem with a supercharger in a transversely mounted FWD setup is that it makes working on anything else a major pain in the butt. The supercharger and the plumbing pack what space is left under the hood.
I’d also recommend against the K&N CAI. The oiled filters have been knowb to cause problems with contamination of sensors.
What you mnay want to Google is an ECU reprogram. Stock programming is deigned to prduce acceptable performance with maximum fuel efficiency and minimum emissions. There may be a program out there that’ll compromise the fuel effficiency and give you some more power. That type of change is less likely to cause other problems.
And keep your expectations realistic. This was not designed to run like a Shelgy Cobra. It’s a Focus. An economic mode of transportation.