Mr. Mopar had a set of those headers and said they banged on everything no matter what he did so he pulled them off. 240 lost a bunch of torque removing all 4 cats. As for me and the NW downpipes, I gained a bunch of power up top, the torque ....... I don't have old low speed dyno sheets so I'm going by butt dyno numbers. Putting around at 1500 rpm and cracking the throttle results in lazier acceleration without the cats. At 2500 rpm I don't notice a difference. My peak HP numbers are higher than torque which could be the lack of cats, I don't know. I'm happy with the downpipes.

Les