It's actually not that hard of an install. I'll give you pointers if you decide to buy the piping with the filter included. I responded to your pm.
TEAM DURATEC #512 ST CREW #100
2005 Ford Focus ZX4 ST
Focus Sport Cool-Flo v.1, Focus Racing Cat-Back w/ Magnaflow HFC, F2 Header, Focus Sport Tune 93 Octane, Saleen Suspension Kit, Rota Slips 16x7