The noise is valve train.
If you go to 15W x 50 oil it will all but eliminate the valvetrain noises, hot and cold.
The motors are noisey beacuse Dodge uses a very high/fast bleed off lifter. The factory lifter is similar to a Rhodes lifter. It is done to make the engine idle a little smoother and cleaner, emissions wise. This is great in theory but seldom works as well as the engineers say it will. I have used high bleed lifters in a few motors I built, and eventually took them out and installed a low bleed racing hydraulic lifter. Better overall performance. And before you ask, ("where can I get a different set of lifters for my motor"?) there are no low bleed replacemants available.
Shaft roller rockers will not make any more HP in a Gen 3 Viper motor than stock rockers.
Gen 3 motors have a 1.7to1 ratio to start with, where previous generation Viper motors had a smaller ratio which allowed for upgrading the rockers to a higher ratio with a corresponding HP increase. Shaft rockers do maintain a better geometry and will help to make the valve train last longer. The roller tips on the rockers keep the valve stem from being side loaded and keeps valve guide wear down.