Quote from blitzfist >>  Don't do it.  The increased horsepower will be negligible and you will change the back pressure. The engineers designed in a certain amount of backpressure and the variable valve timing software is based on it.  Your engine has variable valve timing and if you remove the resonator and muffler, you throw all of that precise engineering out the window.  You will also eventually be annoyed by the noise of your own car and reduce its value.  Inspection laws very from state to state so not sure there.

 I'm in NJ and I'm pretty sure they're illegal but I've heard mixed things. As far as the engineering, I didn't find any of that online, interesting to note. Thank you for that!