Perrin single tip single pipe (they have dual pipes out now). No drone, relatively mellow until you get on it, then SWEET at wot. At least with a catted Helix dp. Dk how it would sound w/o a cat. It also has the benefit of being oval and semi stock looking. Not something that super stands out to the po po.

An audio comparison of different setups:
Exhaust Video Thread - Page 7 - Normally Aspirated Powertrain - NASIOC

There is also a chart on NASIOC showing the db levels of different exhausts so you can choose one that suits you. I did a quick search but couldn't find it. If you dig a little I'm sure you can.