It's all in the eye (ear) of the beholder (Police). When I first got down here and drove my TA around I had a 4 inch electric cut out exhaust valve that dumped it right out of the passenger fender. The main exhaust split for the 5 inch (out of the turbo) to dual 3 inch and spin tech mufflers. The exhaust then went out over the axle and out the back. Even though the dump was open right outside the passenger window, there was very little difference in sound level when I opened or closed the valve. After that I never closed it. The only difference was the wastegate exhaust. The outlet for the wastegate went back into the exhaust system right before the open dump. Because it is straight out of the header pipe before the turbo it is louder when the wastegate opens, and you could hear it pretty well with the open dump valve. But under normal driving and even an inspection you would never hear it. My Cats wasetgates (50MM each) are in the 180 pipe right out of the header collector--
and it will dump out of its own 2 inch pipe. No matter where I tie into the short open exhaust outlet it will probably be a little loud, but only under boost again. If I run a full exhaust later I can run it back into the full system.
Mark