Not in an A-body but I got a few 5.9l questions

Keep in mind, the EFI system is speed density. Items added that add air flow (intake, exhaust, headers, cam, etc) will help because they make the engine more efficient, but the computer does not have a way to gauge the additional air flow, and you will not get the FULL benefit that could be achieved with your new air flow parts.

I'm not saying not to add them, but the EFI system is dumb, and as such does not allow all the HP and TQ that could be obtained. I wish it was a mass air flow sysstem, so it could wring out all the possible HP, instead of leaving some in the tune.

For reference, I have K&N, Pacesetter shorty headers, Magnaflow converter and exhaust, and major porting on the heads and intake manifold. I also ditched mechanical fans for electric.