catalytic converter low efficiency

[JLS781]

my 2005 5.7 hemi ram has a check engine light on and the codes coming up are for both catalytic converters working "low efficiency". can these be replaced by bolting new ones on or do they have to be welded? can anyone recommend where to buy new ones that are descent quality and price?

 

[fastf]

Ok can give you a little advise you need to check your coil packs one misfired to screw your cats up I had one misfire on my wifes car and I repaced both the coil packs and cat .I still don't know how the car ran as good as it did but the cat was bad on the inside.I would check around heck if you poor like me check Ebay they sell magnaflow cats and yes they bolt to the exaust manifold you will have to have it tact welded where the left crosses over to the right cat to the muffler.