It was a bit quieter than my catless Cobb - the resonator helps a ton and there was no drone at all in the car. I love the sound of the Invidias. It's definitely not stupid loud or obnoxious, though it's definitely not stock. My buddy ran it with the stock DP with no problems.
I'll do 350 if you pick it up this weekend - I don't have my wagon back yet so I can't transport it up the hill, and it's taking up space in my garage. It's in the original box and everything.
