5 star tune question?

[AbelNavyvet]

I have a 2006 EXP. XLT 5.4 I'm looking to custom build my exhaust and need to know if I cut off the cats, can a 5 STAR Tune delete the O2 Sensor Check engine light? I'm looking for performance mainly, What size pipe should I use? I'm building it so it wont be to restricted. what you think? please give me some advice.

 

[GAINMOB]

i've been on a few of exhaust sites...2.5" - 3" seems to be standard