2 reseonators or 2 mufflers?

hey I don't know if this is the right section to post this in, but my friend's dad has an Infinity J30 and right now he doesn't have any mufflers on and he's just using resonators. He's wondering if he removes the resonators and then runs the pipes back out and attacvhes dual exhausts will it add or take away power? Thanks for you time

it wont make much of a difference if the muffler is already gone. i believe the resonator is basically to change the exhaust sound. the cat or muffler is what changes backpressure.