there will be a huge diffrence in noise with turndowns then out the back.
In my street monte,it was over the rear for awile never vibrated the car.
Then I wanted to go faster and cut the tailpipe off and put turndowns on it and wow,it rattled everthing.
I asume the noise was boncing off the ground.
I think if I would have turned it out in front of the rear tire it would not have been so bad.
JMO