Never heard of them, have you considered the other popular brands like dynomax or pypes etc? Thats what most guys on here go with.
But looking at their website they have 3 pages of sound clips to listen to on cars, no pontiacs but since every motor is built different, one guys car/engine will sound different than another one built differently, so cant really tell what they will sound like on your cars.
https://paradoxmuffler.com/sound-examples/