I have a 2001 530i, with the optional sport package. I have had a turbo and a cold-air intake added by Lineback Interprises in Dallas, TX. I have gotten all of the audio recently revamped, also adding MB Quart Pro Mids and Highs and a JL Audio W7 woofer. My big question is, what would you add next? I will need tires soon, but that is something I am not very worried about. I am considering exhaust, but with the straight 6, i'm not sure if I will be able to get the desired sound I am looking for. I really don't want it to sound like a rice racer (ie. a honda civic with a fat muffler on it.) I would just like a little more sporty sound out of the exhaust. I have review various threads on here with different exhaust reviews, but I want some honest opinions on this topic. Also, if you list any products would you mind putting the prices next to them. If you don't think the exhaust is needed, what else would you add? Thank you for any replies.