Before I add any new Ex. pipes, I always coat the insides w / VHT paint, roll it around to coat it all thoroughly.. & let dry..
This helps in a couple areas:
(1) the internal paint coating retains heat (like header wrap). which promotes Ex port velocity.. (kinda like Hooker's step-tuned Big pipes, cept they use ceramic) I have on my softail..
(2) really helps prevent bluing, over time they likely will get a slightly gold tone at the heads...
If they have heatshields, I'd get em too..
And if you are gonna leave em open (no baffles) I would add torque-cones..