exhaust tips

[WJ 2000]

I know that some motors need back pressure to run properly, I'm not sure about the 4.6's if you should open them up a little,my main concern is loseing some torque
and I really dont want to lose any torque, after spending all this money in my motor its the last thing I need. I'm thanking on adding a Borla exhaust header, Calif approvel
cat, and Magnaflow exhaust muffler, I'm sure all these parts will add some more HP, but what about torque? will I win''' or lose'''' ?? whats your committments