I wouldn't unless you like to make your plugs even harder to change out and want to replace plug wires often. In my experience headers aren't much of a gain for stock usage. They only give notable improvement if you consistently run in excess of 5500 RPM. Most would benefit if they stuck to an exhaust system where the front pipes matched as nearly as possible the outlet diameter of the stock cast headers and if running single exhaust on a V-6 the system after the union of the front pipes shouldn't exceed 1.5 times the diameter of either input leg. If running true duals all the way back the manifold outlet diameter should match the pipe inside diameter all the way back including through whatever muffler is installed in each side. If additional performance gains are desired with a full-dual system a cross connect pipe should be added up front as far forward as is practical ahead of any mufflers or convertors if so equipped. Equalization of flow pressures thus attained will add performance and power. Thus spaketh the exhaust specialist for the A J Foyt race team to my ear many moons ago when I still worked in a Ford dealership and had occasion to service his car thus developing a friendship with him. I have used this method on several vehicles of all different makes and models with excellent results. Disagree if you like. All I'll say is it works.
On a flow related note, you used to be able to buy what was called a "Sonic Turbo Muffler". It was the highest flow rated muffler I've ever seen and had a deep idle tone that dissapated into a quiet whooshing sound as rpm's increased from about 1700 on up. Very quiet at full throttle. If memory serves flow rate was 96%. They used a parabolic reflector which reflected the incoming exhaust noise back into itself which had a noise cancelling effect. Odd concept but sure worked well.
2001 CC LS, pewter, stock, 4.3,Wait4meperformance, CFM throttle blade, Helix throttle body spacer, 4spd auto, 3button electric 4x4 shift, heavy duty factory suspension, Bilsteins, 1" rear wheel spacers, skid plates.