The cat is WAY out of the way of the subframe connectors... I think Razor is right. I haven't welded my GW subframes up yet but the passenger side does get REALLY close to the braided flex coupling in the downpipe. Heck, I'll have to remove the lower portion of the factory downpipe to get the welding torch in there. You can always section the downpipe in the straight section before it bends to the flex coupling and remove about an inch then weld it back together... that'll give you plenty of room.