effect of Catalystic Convertor upon MOT emissions
 

On the average modified scooby the cat in the up-pipe, if there is one is usually the first to be removed. That leaves the one in the downpipe and a second in the mid or centre section, both of which will usually be high flowing items. Has anyone any idea if one is more vital than the other to an mot emissions pass? I know some decat the downpipe and retain the centre cat but is it still possible to get a pass having done that.
thanks for any input
Trev