what size exhaust

[82c10]

i have a newly rebuilt 350 bored .40 over, 268 lunati voodoo cam with matching lifters, springs, locks, and retainers, , h345np hyperuetectic pistons, 76cc cylinder heads, stock rods, and reground crank ( i don't think that matters), and a double roller timing chain, the specs on the cam are duration at .050 .227/233, the advertised duration is 268/276 the lift is .489/.504 the lobe seperation is 110 and the lobe centerline is 106 , hopefully i will be getting a performer rpm intake manifold, and a 650 holley double pumper, hopefully soon i will bump up the compression to 10:1 and get better flowing heads, anyways what size exhaust should i get, 3" or 2.5" it will be duals going into force mufflers, turned down before the rearend, or i might get it going out in front of the rear tires, it has headers on it also