audio set up question

knightjustice

vehicle: 2013 - 370z
current set up: stock radio and speakers

what i would like: just add in a 8" sub for more of a bump when listening to unce unce unce

so far got an idea of getting a jl 8" with the 500 series amp from jl as well. i could upgrade the amp to the 600 series. but for now i think the 500 series is plenty. i dont want to be the loudest

also if i get the sub do i might as well change out the side speakers and tweeters for the mids and highs for clarity?

would i also need to upgrade the radio too? i just have my ipod hooked up on the aux port. im not sure about the hook up on it, but i have to i just want a single din radio (bluetooth would be nice). i dont need a double din/screen