How do I get the front cat gasket on?
 

The one that is aqua marine in color (mine was, don't know if they all are), and is made of coils of fabric-like material with some thin metal holding it together.

It's a very tight fit over the end of the pipe, it's like putting a bike tire over a rim, it goes on most of the way, and then it needs to be stretched a touch. Not too hard with a bike tire, but I had no idea what to do and ended up wrecking it by trying to gently tap it into place.

Any ideas? This is the gasket, number 61573. Fel-Pro 61573 - Exhaust Pipe Gasket | O'Reilly Auto Parts

It shouldn't be that hard.
I buy the dealer gasket, they slip right on.

Wrong gasket, it should drop right on the end.

It's a Fel Pro gasket and several websites said it's the correct gasket and part number. :dunno:

It does make sense that it should slip right on, I see no reason for it to be so tight.

I tried another Fel-Pro gasket today. Same problem, so I called Fel-Pro and made sure I had the right part number and was getting the correct gasket. Other than that, the guy didn't have much advice. He suggested it might be an after market cat, but I looked at a lot of pics online and I see no differences at all between my cat and the pics, I'd think an aftermarket cat would have some minor differences, such as in some of the brackets, etc. The cat has no writing or numbers on it, so... :dunno:

I did buy the car with a test pipe installed and the cat in the trunk, so I have no way of knowing what the history of the cat is. Anyone know if any changes were made to the factory cats over the years?

Our cat/resonator isn't exactly an off the shelf item. If it looks like our cat, it's most likely an OEM. What about the gasket that was on the other pipe? You should really just try the OEM gasket. It's $13.50 from mazdatrix, I can't imagine it could be that much more from a dealer.

Part #40-3050-N3H1

Thanks for that part number, Reoze. I think I'll do that. I did what I normally do, and bought from one of my local auto parts stores, but Fel-Pro seems to be what they all carry. After I bought these I noticed that Atkins carries on that looks slightly different, and might not be a Fel Pro.

Interesting, any idea if mazdatrix has all the part numbers transposed like that?

I ordered one from Atkins Rotary a few days ago. It got here quickly and fit the cat properly, unlike the Fel Pro. Label on package says it's an official Mazda part. It cost a good bit more, just under $20 with shipping and tax, vs $6 or so from the auto parts store, but it's worth it since it actually fits and the Fel-Pro doesn't.

Thanks for the update.
Not too many things with our 8s are cheap.
Best to try as close to OEM as possible to avoid hassles.
Regular maintenace items like filters, ignition, and brake components are pretty standard items and easily attainable, but less frequently used parts are more of a dealer or niche market item.