Lexus Repair: Big Problem HELP!!, lexus gs 300, combustion chamber

Question
I need your knowlesdge and expertise! I was told there is a rattling sound inside the catalytic converter of my 98 LEXUS  GS 300 and that it needed to be replaced. Wer'e talking $1600. Is it really time or can I wait a little longer? I have about 12600 miles on it with no hesitancy or engine lights coming on. Please give a detailed response so that I(female) can really understand.  Thanks a million.  

Answer
Hello Kim,
 Catalytic converter is the common failure on most of the GS and LS.  This is the beginning of it, The job of cat. converter is very simple.  It burns off the left over gas from combustion chamber, so we don't pollute our ozone layer. You have two 02 sensors, one before and after the cat. converter. The rear 02 sensor measure the efficiency of your cat. If it's out of range your CEL will be coming on.  I wouldn't worry about it too right now. You are right the cost of the replacement is very expensive but if it does need one.  I would stick with Lexus parts. NEVER NEVER REPLACE THESE CATS. CONVERTER WITH A AFTERMARKET UNIT!!!!! WE'VE BEEN DOWN THIS ROAD. The cheapo converter won't do the trick!!!
JP IMPORTZ
DALLAS INDEPENDENT LEXUS AND TOYOTA
SERVICE, REPAIR AND PERFORMANCE
WWW.JPIMPORTZ.ORG
214-221-3135