Originally Posted by ped

The only real reason I can see is that different combinations of cats, exhaust headers and catback exhausts would make picking one size Helmhoktz resonators impossible. But they could at least put one on for the base config of stock cats/headers with their catback exhaust. This is poorly-discussed aspect of their exhausts on this form as this is the primary reason I will be paying labor costs again to have this exhaust removed, plus taking a loss in the form of a restocking fee since it now not be sold as new (it's all of 48 hours old).