SC400 Catalytic Converter? Easy?
 

Guys,
My beloved SC400 just failed emissions (NO level too high).
I already cleaned out my EGR valve and connecting area.
I have 8 new spark plugs, 2 new caps and rotors, 2 new coils, new wires, new PCV valve, cleaned air intake manifold, new air filter of course, car runs like a dream, it's super fast, it's super strong, completely stock, done the Chevron Techron treatments regularly, have 93 Octane, exhaust doesn't smoke, doesn't smell rich, isn't out of the ordinary. I just simply failed the NO test.
I believe it's time for my cats to be replaced. I have located them. They are bolted on. Question: has anyone changed them out on their SC400, and is it an easy job? Obviously, the 2 bolts closest to me appear to be easy, but the ones at the top don't appear to be as accessible... any thoughts here would be appreciated. I'd just buy 2 rockauto cats and 4 sensors (the two up-system and 2 out-system. Is there any modification that I need to be warned about? I have not seen any youtube videos or seen any threads on cats for an SC400. Let me know when you get a chance.
Thank you, and God bless!
BigOSC400