Does your X-pipe exhaust drone loudly?
It's the muffler that drones and the dumps slaming the sound on the floor bouncing back up that amp it up. The X pipe is a good helper in scavenging. It shouldn't be hurtful to the ears.
Run tail pipes, direct the sound away. I have turn downs at the bumper and it did make a difference even at the rear of the car. The sound isn't bouncing of the houses, just going down.