I have the setup you will have with stock exhaust back to the axle back. One of my friends has the axle back and test pipes and it is much louder. I used a decibel meter app on my phone and at about 2-3 feet his car was at 80 decibels at a warm idle. We are doing a dyno day Sunday and I can let you know how loud both of our exhausts make as well as power differences. As for sound, my friend's exhaust sounds a bit higher pitched than mine under acceleration but at a cruise it sounds about like mine, just louder. Here is a video I took of to give people an idea of how my exhaust sounds, as I said his has a slightly higher pitch than mine, also it has a bit of rasp to it as well.