My '97 makes a terrible rattle when it's cold ... gets better after it warms up. I thought it was the CAT and was hoping that it would Fail the Calif Smog Test ... because then I could avail myself to the $500 that the state will contribute to having it fixed. BUT it past with flying colors ... even though I took it over cold, and usually you want it heated up to Pass.

So I figured the rattling must be from a loose Heat Shields?

I took it in for some other servicing today, and the authorized Toyota Dealership said that it WAS the CAT making the noise ... and a new one was $900+.

Can anyone suggest a cheaper source of CAT's?

Could I temporally remove the CAT and replace it with a straight pipe, without adversely effecting the engine?

Fixed ...

Wow ... oem Toyota Previa CATS are expensive, over $900 ... there are a lot of Previa's in this area ... and apparently thieves will cut out the cats to resell!

I was looking on "EBAY" and there are cats for sale there that are very reasonable not sure if they will work or are oem but worth the look hope this helps bixxl 92 previa

Sorry to hear you had to replace your cat con at such a price. I have a 94 that would rattle when cold until warmed and I too concluded, after inspection, that the heat sheild on the cat had lost 2 of 4 spot welds. When the other two went, I drilled small holes next to (can't drill a weld) the weld and inserted nuts, bolts and lock washers. Solved the rattle and saved the cat.