My recipe on our 5.7 hemi r/t:
Corsa cat back exhaust
High flow cats and mid pipes
Kooks long tube headers
K&N intake
Throttle body
Diablo custom dyno tune running on premium pump gas
It's a great setup with room to grow and I did it all (except the tune) in a driveway
Some things to consider though if you're buying new:
-These will void warranty unless you put stock parts back on when you take it in
-if you live in the city you won't pass emissions