I just got a windscreen for my '98 323 and man, does it make a huge difference. I can now carry on a conversation with a passenger or on a cell phone without getting a sore throat, and my radio can return to a lower volume, saving my speakers I hope...at least until a really good song comes on.
If you don't have one, try it. $399 at the dealer, but I bought mine off eBay for much less.