Stock exhaust to Catback
 

I have a 2008 F150 XLT 4X4 , Can I change my stock system to a Cat Back System. My system is stock 2.5" and I want to put a 3" C B system on to help the engine breath and improve performance Is this possible.

It's not going to improve the performance unless you get a tuner.

If you want to hear your exhaust, go for it. If you want to improve the performance, don't bother, the stock system is low restriction to begin with.

x2. For sound, get the exhaust. For performance, just get a custom tune.