There isn't much sound difference with or without the 3rd cat or downpipes. I still do have the factory resonator installed, I'm sure tbf at helps alot. Before I got my tune files for my '13, you couldn't stand driving the car. Rasp and drone where terrible, believe it or not, after I tuned the car, rasp and drone were all but gone. I have very little drone or rasp now, wife and daughter never complained. My only complaint was with the tips, they had small rust spots that showed up fairly quick. I've been complimented alot on the sound.