Aparently the way I understood the way it works is when you are at low RPMs it is more quite and you still get that low end power that some may lose when they throw a huge muffler on their cars and when you really rev into the higher RPMs it has a valve system that is disengaged letting that rumble back into your exhaust system and that heavy flow of air. Just thought it was a cool idea and can't seem to find it online anywhere in america