Pontiac Firebird 1967-2002 - Firebird Lt1 Catalytic converters

Hi, was told by the gm dealer that i have to change the catalytic converters, the car doesnt go thru the smog test, the car doesnt have any engine check error and any noticeable engine problem, maybe get a little hot when idle or on a light the temperature get above the second mark and very few times raises to the third mark just below the red mark, and high fuel consumption like 13 mpg on the city. What do you think, could be the cats?
If the cats are the problem i already saw the magnaflow ones, the universal ones part number: magnaflow 99005HM, does it fits the car? the magnaflow web page states it fits, but the dealer says it doesnt fit the drivers side. Anyone installed this cats or know if they fit or not.
Thanks

Agustin Cervantes
Firebird Trans Am 97 LT1

I think there is someone in The Tx classified section selling some low mileage ones if you are looking for stock replacements.

take them off and tune them out.