In my experience, a NA car is more loud than a turbo car. I had a 2G NA eclipse with a full exhaust (4-1 header, 2.5" hi flo cat, into 3" Megan Racing catback) and that thing sounded wicked (not to mention loud). I have my full 3" turbo back exhaust on my supra (megamouth DP, 3" testpipe, 3" RSR GTII) and it is loud, but no where near as loud as my NA was. BTW, the the egines where 2.0L and 3.0L respectfully and the smaller one was louder (could have been the turbo deadning the sound of the 3.0L, but I know for a fact the RSR is considered to be one of the louder exhaust for the MKIII.)