Catalytic Converter Options

[es300_98_NY]

Lexus ES300 1998

Dear forum members,

I am a student and always looking for cheaper options for my car repairs.

2 months ago my engine light came on and my mechanic thought it was the EGR valve and the selenoid, so he insisted on replacing them, which we did. The engine check light came back on a week later, just before i thought i will pass the NYS inspection (still can't pass it).

I took the car to another mechanic, who diagnosed it with faulty spark plugs and replaced them free of charge if the light comes back on, well it did reappear the next day after 20 mile drive. After he took them out - the new spark plugs were completely burned, so he immediately pointed the problem towards the catalytic converter.

His price for the part and labor is $500, and only Lexus made (as per mechanic). Gave me a small lecture that without a new cat converter- it will damage the new EGR and selenoid along with the spark plugs.

1. Can i bypass the dealer parts and use much less expensive cat converter ?

2. Can the new cat converter be installed via smoldering (so i don't have to replace the whole exhaust )?

Thank you for any input.