M45T1N

Hiya, I own a 2002 Lexus GS430 which unfortunately now requires a combination of a possible 3 cats and 4 oxygen sensors, I am wondering if anybody knows of any after-market uprated cat/sensors that I can fit, a possible aussie pipe would be awesome if it is possible to get the emissions right and I am also looking at other modifications that are available to my car. I am currently finding it rather hard to find any kind of upgrades available to this particular car. Many Thanks To Anyone That Can Help Martin Hoare