The stock DP is a double-wall with an internal flex. I have heard of these separating and causing a tick or rattle.

This is another option for a cat that may work with your stock DP flange, and may even fit your car better than the Hogan (because the cat is cylindrical, rather than oval):

http://store.summitracing.com/partde...5&autoview=sku

Here'* the manufacturer'* link:
http://www.car-sound.com/02product/d...irectfit=23437

(Nowhere does it list what the inlet/outlet diameters are...you should call car-sound to find out)

I'll tell you what, though...you may not need to change out your cat. The stock cat on my '04 LeSabre is a small, ~10" long "bullet" style cat (compared with the 2 foot long, 10" wide stock monstrosity on my '98 LeSabre )

If your '01 Bonne has this smaller type cat already, I'd say leave it in. Especially if you're sticking to a stock DP, which necks down to like 2.25" inside anyway

I had the same rattle in my exhaust. I found that the stock down pipe has some sort of internal flange that breaks off at the weld and causes the rattle. I put on the same stock pipe again and it has been fine ever since

Just a little update, changed out my downpipe today and it took care of problem. No more rattle. Cat still good, so that will stay for awhile. thanks for all the comments and suggestions

Wow thanks for the update. I can now say I have heard of a rattling downpipe.

Is the down pipe the same thing as the flex pipe? Dealership said my flex pipe had an exhaust leak. Was wondering how much it would cost me to fix. Getting kind of annoying.