Really Bad (was Good) catalytic converter from MagnaFlow
 

http://www.summitracing.com/parts/mpe-59959/overview/

After a variety of searching, I ended up installing the cat linked above (MagnaFlow 59959), and it has been doing great for a few months. I saw that someone out west had recommended this cat, and I thought it would be worth a try given the price.

I had a local shop weld it in place of the Bonez cat that had failed. The shop did a great job. They just had to lengthen it a little with some extra 3" pipe.

I also don't want to totally bash the Bonez cat (Rotary Performance Super Cat). I'm pretty confident that it died an early death due to two ignition system failures. RP also offered a reasonable price to weld in a new Bonez cat, but I couldn't afford to ship it off to them as this is my only car (and I don't have a catless midpipe). I drove around without a hollowed out cat for a little while until I got the LS coil upgrade from Bennett Built, then I had the cat put back in.

Anyway, I think this part is a reasonable option for people who don't want to spend $1200 on a new factory cat or can't find a decent option in the used market. I also realize that the HJS high-temp cat from Europe (also sold by Pettit Racing) is a quality option too. However, this one is certainly more affordable. We'll see how it holds up now that the ignition is healthy.

***UPDATE: This cat failed eventually. I ended up buying a stock-ish replacement and managed to avoid its destruction.***

How many miles?
Please keep us updated on it.
I am interested to see how long it lasts.

Bonez = Supercat

they fail early as I recall from past posts ...

I managed a fail here too. I ordered a Magnaflow 59959, metal substrate, stand alone, 3" cat. It fit nicely in my Turbo XS catted midpipe, right where the old one went. The reason for the replacement was the smell Turbo XS was a 100 cell that just finally wore out. Smell came about the same time as the error code.

This was in April 2019. As of January 2020, the media had broken loose (metal media stays together) as was slowly moving from the wide area where it was supposed to sit, down through the neck, with the holes getting smaller all the time and choking off the exhaust. Searching for issues I found this post. I missed it the first time around. Hoping to raise a bit of awareness.

Also, looking for a safety net. I am thinking about drilling the next one in 3 places, just downstream of the media, tapping the holes then inserting some 3/4 inch long machine screws. Then either welding them or inserting a nut on the back side before I install it. That way, if media breaks loose, it cannot get to the neck. Thoughts, Opinions and Alternatives are appreciated.. This approach makes the cat a consumable, but done this way they are inexpensive. I just did not realize this failure mode existed..

Thanks,

And, if OP wants to change the thread title, it is recommended.

https://cimg4.ibsrv.net/gimg/www.rx8...36333b70ce.jpg
Working its way out of the housing, into the pipe.
https://cimg2.ibsrv.net/gimg/www.rx8...10d54db739.jpg
how smashed it was when I pushed it back.

Yes, that won’t happen with the HJS cat converter. This is one part where you get what you pay for.

I updated my initial post. I'm not sure how to change the thread title.

The Magnaflow cat failed just as it did for 04Green after several months. I bought a stock-ish replacement, and it was good enough to not fly into a million pieces. The HJS cat is the way I'd go if I could do it all over again. I'd also have to figure out the source(s) of the electrical problems that I had with that car.

I traded in my RX-8 in Feb 2018 on a new 2018 WRX. Before then, I was keeping the RX-8 alive with daily trickle charging of the battery. I was battling this problem for quite a long time, and it only seemed to get worse with the ignition upgrade. I still think that the electrical system is the weakest link. It was my daily driver, so I could never take enough time to tear it all apart and figure out the root cause(s). (I did replace the alternator, fixed the ground points, and did many other things that should have helped.) In my case, I think the inability for the car to keep its battery charged and to generate enough electrical energy to create good sparks lead to very high exhaust temps which then lead to cat failures (and can lead to engine failures). Of course, I was always fighting the exhaust system on my RX-7, and it had a simpler electrical system with no spark generation issues.

In the end, the rust monster just took over. I bought the car from someone who drove it in Chicago winters, and I did not realize the extent of the rust damage that it had then. It only got worse driving it in Ohio winters. The car had holes in the subframe, and the front suspension mount points were in rough shape. The unibody developed some serious holes too. I just couldn't deal with it as a daily driver any more, and I had no room to make it a 3rd car/project. I do miss it as it was/is an incredible car. I still smile from my memories of driving it at a test and tune evening at MidOhio's road course.

@ Team

Will look at them next time. For now, I have a FlowMaster, Really impressed with it. Where the Magnaflow was just media squished (held firmly is what I think they said) in a pipe, this one has the media bonded to a piece that is welded in. I added a SS rivet to serve as a stop if things start to move, and is something I can drill out to inspect for movement. The one I really wanted was only available in Australia (https://www.tuffcarparts.com.au/3-10...converter-poli) It was a 100 cell. HJS will make me learn how to weld a lot better than I can today.

I also learned the symptom, slowly creeping negative Long Term Fuel Trim.

Mike