BlueBomber,
I won't kid ya, it's significantly louder. I don't mind it but I could understand why others would. From the inside, it's not that much louder. At higher RPMs, the car really screams. At lower RPSs and it idle, it has a deeper growl with a good amount of back firing.
I know that this is not the sound that everyone would like to have. But, if you are looking for some better throttle response, I would do it. I paid around $450 including the installation. You can't go wrong. The sound (IMHO) is pleasant and it's not annoying. I think this has been one of the best modifications that I have made to the car. I love it!!