Welcome HOME. Good Luck with your build. As others have pointed out, go with a theme and what you like. Do lots of reading.
I personally went with 3 categories, performance, handling, cosmetics. I have created a good balance of all 3 and my spread sheet of money spent proves this too.
You can check out my build thread for some ideas.
http://www.camaro5.com/forums/showthread.php?t=77861
As for exhaust sound I am partial to mine.