Improving? You can start with the rear. Get 3.09 gears and see a huge improvement you will. Then a set of bigger tires. This will help putting down the power you already have.
The 5.7L is a nice platform to modify. The entire intake system can be upgraded. A 392 Intake with a Fastman Throttle body and a JLT intake system or a Hellcat Lower Air box with the intake tube and front mount are 2 good ways to go. Then you use a drop in Hellcat filter or a K&N.
A cam upgrade is huge for the 5.7L. Might want to to a lot of research on what cam is right for you, so many choices.
Depending on what year your R/T is , you can play around with the exhaust. If you have the Active exhaust I'd leave that along. If you have an older R/T like 2016 or older then check out Flowmaster's Cat back system.
Headers are a very good idea as well as high flow Cat's.
Once you go down this path, you will have to unlock your computer and get a tune unless you have a 2014 or older. I believe they are unlocked and can be tuned. 2015 and newer you have to unlock.