Auto Parts: Manifold Catalytic conv., mazda 2000, california emissions

Question
I have a Mazda 2000 - 626 V6 2.5 L that is losing power when excellerating.  I was told it was the cat. converter.  The mechanic ordered the cat and he ordered the wrong one.  He now says that the converter that is bad is the manifold Catalytic Converter and can only be purchased from Mazda dealers. And would cost around 600.00 to buy the part. Is this right?  I can't not afford to replace this at that price.  Could there be something else wrong?  I was also told that it could need the fuel filter replaced. It does have 166,000 miles on it. I don't know what to do.

Answer
    I've looked good and hard and here's what I've found:  The center converter for 49 state cars is available from Walker (NAPA).  But it sounds like you are looking for the converter in the manifold pipe.  This is only used in California emissions cars, near as I can tell.  Since the non-converter manifold pipe sells for over $400, $600 sounds reasonable for the converter assembly.  An exhaust shop has a test that they can do to determine if your loss of power is due to a clogged converter.  It measure back pressure in front of and behind the converter.  I would advise going to your local Midas (or whatever) and having them perform this test.  If yours is a California car you are going to have to break down and buy the part from the dealer, no one else makes it.  The only option to this would be to have the existing converter repaired.  Eastern Converters in Philly can do it, there may be others.  I have had good luck dealing with Eastern, they know their stuff.