...Not a problem at all!!
The driver side exhaust has a little flap that runs off an actuator that opens/closes at different RPMs and typically stays closed at idle to increase back pressure/let allow for the cats to heat up/etc...
I actually disconnected this flap (it always stays open now)... The mod is called "Golf Tee Mod" where you disconnect the vacuum hose from the actuator and plug the hose with a golf tee (I'm not kidding) and cover the exposed inlet on the actuator with a vacuum cap ($0.62 at Part Source)
The actuator is located to the left of the driver side muffler... Lay down on the floor and look up, you can't miss it! Looks like a wastegate.
PIC:
http://img301.imageshack.us/img301/7075/pic1f.jpg
This doesn't effect the car in an adverse way whatsoever and will not throw a code on the ECU (so the dealer will never know)... It WILL however give you a slight, sexy change in tone of your exhaust (a little bit deeper and meaner)
For 62 cents and for less than 5 mins of work, why the hell not!
And you can always reverse the change in a few seconds, too!