You don't need to be obnoxiously loud to get noticed. Just get some headers and Thrush turbos and be done. I had 18" glasspacks at first and they sounded crappy. Theres a few kids at school with Flowmasters on there trucks, they aren't even competition compared to my turbos. My 68 is "quite rank" as my dad says

, but its not obnoxiously loud by any means. It will talk to you when the secondaries open though. It has a true old school sound to it, I remember once I pulled into a gas station, and this old guy was getting gas, and he says to me "Kid, I haven't heard anything that has sounded that good since the late 60's." So I took that as a compliment.
So you don't need to be loud to prove a point, you just need a nice sound with muscle to back it up IMO.