3" or 2.5" exhaust (pics)

First off what I have is

.030 over 360 10.7 compression
Holley HP 750 with mechanical secondaries
Eddy Performer intake
474/474 Mopar cam
Accel 300+ ignition
TTI headers
4-speed transmission

I am trying to decide what size exhaust I really need. I was going to go with 3" and bought the 3" collectors when I bought the headers. Then I read on a website that any motor making under 450 HP dose not need 3" exhaust. I don't believe my set up will make over 450 HP maybe 400 at the most. Which ever exhaust size I get I am going with a X-pipe and Flow mufflers. I just don't want to lose low end torque but find out later for some reason I should have went with the 3" I already have 2.5 Flowmaster mufflers that I can use if I go the 2.5 route.

What do you think I should run?

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