2.5 complete exhaust VS a 3.0 complete exhaust

I just got dougs headers. Now i am going to do a x pipe or h pipe dont no which one yet and either 2.5 or 3 inch exhaust. I have a 360 with 10 -1 compression, rhs magnum heads, comp cam with .545 lift, edelbrock magnum air gap intake, holley 770 carb. I don't no how much HP i am making. Does 3 inch exhaust sound to big. Will I lose bottom end torque or is that just a myth?