Grand Prix 40th anniversary after market ideas?

i drive a grand prix 40th anniversary gtp it isnt supercharged for some reason but i am saving money to put after market parts in it right now i plan on getting a ZZP 1.0 pcm and K&N cold air intake system possibly a magnaflow exhaust but other than that i dont know what else to put in it i can get a supercharger kit for 800 but i dont think its worth it what are some other things i can do to add horsepower and make it sound and run better?