do i really need 3" exhaust

Some very interesting information given. Thanks for the thoughts and flow charts. It seems that a 3" system would be the best choice for flow and power but that a 2 1/2" would do the job but may not handle any additional upgrades for future improvements. I don't have to make a decision till summer since I'm no where close to ready yet. I will probably go with a 3" dump just behind the headers. Then decide on what size goes behind that. Clearance and where to exit underbody will play a big part of the size. Since the springs have been moved in I will have challenges with fitment as well. Thanks again for your thoughts and any additional advice.
Rod