Googled it, not sure where that hose is on the XF but will take a look in the morning. Also, now that I have taken a look at the exhaust system mine is stock except for the Magnaflow muffler at the back. You had mentioned you took all 4 cats out of the exhaust running back into the Resi then a single pipe to the muffler, is that correct sir? I am thinking going with a x pipe in place of the rear cats and starting with that for now. The paint job turned out slick and deep, I will get some pics. Just got to the IC pump and will start down that rabbit hole soon.