I was in your position a few weeks ago. I was after a good flowing exhaust that was not loud to go with my extractors and cat.
I ended up installing a Redback 2.5 mandrel bent exhaust, with a high flow muff, and a sports resinator at the end.
It turned out to be pretty quiet while cruising, and gives a bit of a roar when im flooring it, however, it is far from annoying, and not half as loud as some of the other EA's etc driving around.
CAUTION: Slippery When BOOSTING!