I personally feel 3" is way too big, considering out displacement or lack thereof. 3" seems like you would start losing backpressure and power.... I know in my 2005 Mustang GT, it was a big no-no to get exhaust too large because of the huge decrease in torque. Long headers were nice though... Just not wide.

I would definately stick with 2.5" in the crossfire but thats just me.