What exactly would I need to replace on my car to give the exhaust a
deeper, tuner style sound? Is it just the end of the muffler or do I
need a whole new exhaust kit? Thanks!

 

a larger diameter pipe will add to its tone. and volume AND performance.

the catt and muffler combo will change its tune quite a bit. i would go around and try to find a simular car as to your and see if its mods sound good to you. if it does then copy if the owner will tell you what was done.

in a turbo car i found the best sound to be a 2.5 exhaust followed by a high flow cattalitic converter followed by NO muffler.

the turbo will knock out so much sound it will drop your jaw.

i run a turbo on a 2.7 88 legend with the above system.
it is quiet enough to hold a comfortable conversation in the car and the man has never hasseled me about it.

maybe go to a exhaust shop and see how much it would cost to remove your muffler...also ask how much it would cost to put it back if you dont like it and save the old muffler.