Had the 4 into 1 xforce headers fitted to my bf xr8 ute couple of weeks ago. Now it idles at 500rpm not 750 like it did before. The cats were not changed. Had to cut 4 bolts off the bottom of the pipes as it would rub slightly on the antiroll bar. They also rub on the antiroll bar mount bracket on the passenger side some times at idle. Just wondering if any one else has had this problem????????????????????????

First port of call would be the place who fitted them

Yeah...they're rubbish. I've seen a super pursuit with a set and they burnt through the steering boot and one of the bends pretty poorly formed too.