How much quieter would a rear exit free flow exhaust system be than open headers? I've been daily driving with open headers for the past week while waiting on my new Y-Pipe/Header combo to arrive and while it has been a fun experience, It is definitely NOT a setup I'd want to keep, primarily due to the fact that even the slightest touch of the throttle sends packs of small children screaming and running and not to mention the overwhelming smell of exhaust inside the cabin (Been driving with both windows down to avoid carbon monoxide poisoning).

Inside the car? EXTREMELY quiet in comparison. The reason behind that is because with open headers the exhaust pulses bounce between the concrete and floorboards.

Outside the car? I'd say about a 10-20db difference. Which is also a large amount.

Just get a good exhaust on it. You lose a little performance, but kill a ton of the noise. My car is so quiet with the cut-out closed that you can barely hear it over the cars idling at the line when I'm nearly down the strip. Cut-out open its still someone quiet thanks to its lower compression and small cam.

This is cut-out closed: http://www.youtube.com/watch?v=DGWUsr4XU1c


Cut-out open, but you can hear the difference: http://www.youtube.com/watch?v=L9W0d...ure=plpp_video