With any X-pipe, the noise gets noticeably louder. It depends largely on the mufflers that you have. If you are putting Fabspeed or Challenge X-pipe replacements on your OEM mufflers, seeing that you're still using OEM cats and both X-pipes come with resonators, it should be louder, but probably not enough to anger most police here in the states. Don't know about France though.
Now, if you have this X-pipe setup with Race mufflers, that's probably going to be MUCH louder.
