exhaust help and opinions

[bojak]

I have a 5.7 with new headers installed. It has been a really long story to get to this stage. My question is what size exhaust set up should I run for the best performance? Is 2.5" too big? Should I run 2.25"? I will be doing true dual all the way out with no cats. Where I am at, the truck is too old and too big for emissions testing. Also need some advice on where to locate new O2 sensor on the system with no cats? This is really basic stuff to most of you guys but if you knew what the header journey was like, you'd understand why I am trying to limit my headaches moving forward. Any advice is appreciated and all sarcasm is ignored. Thanks.