I just recently bought my 13 spark 2lt and removed the resonator out of the drivers side fender well and left just the tube and have found that the car is more responsive. i found it easier to get onto the highway too. I know alot of people are going to say its the placebo affect but I def feel the difference. It didn't seem to get louder either. Now I'm going to put in a K&N filter and see if that helps any. I need a new filter anyways.