I was curious to see if anyone knew the laws associated with moving catalytic converters on cars that are street driven in the US. I am seriously considering a large single turbo for my LS400 and it would be easiest if I could place both cats on one side and just have a single downpipe split into the two. I do know that I can not get rid of one of the cats since it was originally designed to have one cat per bank but I do not know if I have to keep them in the same spot.