^^^ This! If you don't know why you really should not attempt to tune your own car. It takes a lot of knowledge and experience to be able to tune a car well and you can blow up your engine if you "oops". IMO not a gamble to take.
2009 Ford Focus Sedan SE--Amber Gold Metallic--FS Cool-flo intake, 17" Black Kazera Rims with Potenza S-04PP, Custom 2.5" Exhaust.