fastNA

I have two magnaflow mufflers on my car with the stock piping.The inlets to the mufflers are 2 1/2. I'm planning on staying with them and repiping them out. Here's the question: I have some long *** headers,(roadrace headers with long primaries)after the headers theres the cat then it forms the Y-pipe.When each individual pipe goes to each muffler should I make it 2 1/2? I plan on making the small piping after the header 2 1/2 so I was wondering if I should make the complete exhaust 2 1/2

Rob x-7

2.5" with a converter on the car will be fine