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This is second hand info, so do not take it as the gospel truth. However, when I sold the guts of my precat and also my physically broken stock main cat to a local salvage yard, I got to talk to the yard's "cat man". He mentioned to me that the difference between aftermarket cats, OEM 49 states cats and OEM and aftermarket CARB legal cats is the amount of rare metals in them. The more of the catalytic metals there are in the unit, the better job it does of doing its job. Also, as the unit ages and looses some of its effectiveness, the units with more expensive rare metals in them will still do a legal job of cleaning up the exhaust gasses. The cheaper units with less rare metals stop meeting standards sooner.

Aftermarket cats have to meet a much lower standard of performance and longevity than 49 states OEM cats. All CARB legal cats (OEM or aftermarket replacement) need to meet an even higher standard of longevity and effectiveness so they have the most rare metals in them.

So, the cases and pipes are all pretty much the same. The higher up the chain they are the more rare metals are inside them in order to meet higher performance and longevity goals. That is why a salvage yard needs a "cat man" who can judge the type of unit pretty much on sight. A lower grade unit will have less rare metals in it and be worth less money to the salvage yard than a CARB unit would have, yet they all pretty much look that same from the outside. They do not want to pay you too much so they want to know what type of Cat you are offering them.

So, to your question -- they are all physically about the same but they do not all have the same expected service life or level of expected clean air coming out of them. The better ones look pretty much the same as the cheaper ones but they have much higher amounts of expensive rare metal inside them to do a better job of catalyzing/cleaning the exhaust and to do that better job for a long long time. A cheap one would pass a California smog check for a while, but would start flunking much sooner than a unit that was higher up the totem pole. To try to keep folks honest, the CARB folks require units they approve to be marked with that approval. They do not want sub-standard units that will start polluting prematurely.

Again, that is second hand, but that is my understanding.
Thanks for the fantastic and detailed explanation and description! Makes 100% sense. I guess if you're getting more precious/expensive material inside, it obviously will cost more. The CARB requirment is just one of the quirks of owning a car in California I guess! :)
 

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so is there any hp or tq gain after installing either of the Magnaflow cat or Precat ??
I think it is answer everyone wants to know. :)
 

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Unfortunately, I did short Ram intake, muffler and carb certified magnaflow pre cat all at the same time. People seem to say, intake makes no power, so that leaves pre cats and exhaust. . .all together I got approximately 23 more hp and 25 of torque w the stock ECU. So precat must have given me something.
 

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Update time.........

In one of my last posts about my struggle to put the Magna-Flow main cat into my wife's car, I said I would update later. Here it is.

First -- Magna-Flow has fixed the problems with the fitment of the unit. Ironically, they fixed it in 2010 or early 2011. However, they apparently did not take the old stock out of circulation and I ended up with the first version.

In some of the earliest posts on this subject, one or two folks mentioned the same fitment problems I had and said that they had complained to the factory. It would seem the factory listened and fixed the problems. After my complaints last fall they actually got ahold of a stock MR2 and test installed a unit. It fit fine. I told them that was not possible. After exchanging a bunch of pictures and engineering drawings we finally realized that I have the early version of the unit and that it indeed is NOT a direct install bolt-in unit. They proved that the modified/improved unit fits and I would agree from looking at the pictures. They did the same fixes I recommended to them as I tried to get mine to fit, they just had already done it before I had my problems.

So, if you buy a Magna-Flow replacement main cat, be sure it has an exhaust hanger prong welded to the can of the catalytic converter. My early unit does not, and also has several other fitment problems with flange thickness and stuff. The easiest way to identify the improved part is to verify the presence of the metal rod/prong thing welded to the converter case. That mounting thing will line up with the rubber donut support on the body of the car above the cat converter location.

Even with the mounting difficulties my older version unit has worked fine since installed. If you are just buying one now, make sure it is the new version. If you already have the older version, you should be fine once you get it to mount up. I discussed what it takes to mount the older version properly a page or two ago in this thread. If you can get an older version at a discount, take it and use my mounting suggestions to get it to fit and you should be in business.

By the way, in discussion with their tech folks it was mentioned that this is a better and higher flow unit than the stock converter. I would presume the high flow part of that would mean a bit more ponies from the engine. I cannot feel a significant difference, but do think there is a tad more pep and a slightly more robust exhaust tone, but only slightly on both counts. With the exception of that aftermarket main cat, the car is totally stock, including the balance of the exhaust system. Added note -- I did gut the pre-cats while I had the exhaust system apart, so perhaps the increase in pep and improvement in sound is due to the gutted pre-cats rather than the different main cat. Dunno.
 

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Update to the update......

I gotta hand it to Magna-Flow, they are "upfront" with us customers. A guy from the engineering shop called me back today to tell me that there was some communications confusion between the engineering folks and the production folks. That happens in big organizations, unfortunately. The improved version of our main cat may not have made it into production as early as the tech folks thought and may not have all the fixes, so your chances of having an early unit are pretty darn good if you have bought one at pretty much any time.

As mentioned earlier, they can be made to fit well with just a bit of effort and the making of a thick spacer, so if you need a unit and want to go that route, you should be fine, just use my suggestions for mounting it or work out your own fixes.

They have put a stop on production until they are sure that the production folks and the engineering folks are happy with each other and on the same page. If you order a new unit, there may be a delay in production while they sort things out inside their operation.

I repeat, the good news in this is Magna-Flow's interest in doing it right. Rather than sour my view of the company with all this back and forth, I feel better about them now than before. Since I have appointed myself "update guy" on this, I figured I had better let you know the latest development.
 

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Some good information in this thread. Unfortunately a new cat or exhaust is the next mandatory thing on the list for many of us in California here (2 year smogs) :miserable:
 

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old unit

So I bought the Cali legal mid-pipe (main cat) from one of their authorized resellers but got the old one.
-As noted above the header / cat gaskets did not fit. My local Napa had the part 31332 in stock so I bout two of them and they worked perfectly.
-Also as noted above the cat / exhaust leaks due to the cat pipe not having the step under the gasket. It's a very subtle leak.
My theory is that I can sand down the old gasket and use it as a step for a new gasket.
Napa p/n FPG 61016 is same as the Toyota $50 exhaust gasket. I'm going to try out my theory Saturday.
 

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So I bought the Cali legal mid-pipe (main cat) from one of their authorized resellers but got the old one.
-As noted above the header / cat gaskets did not fit. My local Napa had the part 31332 in stock so I bout two of them and they worked perfectly.
-Also as noted above the cat / exhaust leaks due to the cat pipe not having the step under the gasket. It's a very subtle leak.
My theory is that I can sand down the old gasket and use it as a step for a new gasket.
Napa p/n FPG 61016 is same as the Toyota $50 exhaust gasket. I'm going to try out my theory Saturday.
Please take pictures. I would love to know if your idea works.
 

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So is there a specific part # that is the correct one?






So I bought the Cali legal mid-pipe (main cat) from one of their authorized resellers but got the old one.
-As noted above the header / cat gaskets did not fit. My local Napa had the part 31332 in stock so I bout two of them and they worked perfectly.
-Also as noted above the cat / exhaust leaks due to the cat pipe not having the step under the gasket. It's a very subtle leak.
My theory is that I can sand down the old gasket and use it as a step for a new gasket.
Napa p/n FPG 61016 is same as the Toyota $50 exhaust gasket. I'm going to try out my theory Saturday.
 

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So is there a specific part # that is the correct one?
Sorry I don't know. Magnaflow was zero help for me. Asked me to send in pictures, part numbers, receipts, bla bla bla. I emailed them over but they never called me back. Basically, I feel they blew me off.

So I took the unit off. I compared the old muffler gasket to the new one and the new one was taller and beefier. So I though maybe I could get away with just the new gasket. Well same problem. So I'm going to try the dual gasket experiment. Sorry this is side project so will take a week or two but I'll report back.

-RJ.
 

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When I did my install I had the luxury of a friend with a nice machine shop. We made a spacer to go under the donut gasket out of steel. We started with a VERY large washer from the junk box, it was about a quarter inch thick. We turned it down on a lath until the inside diameter was a snug fit on the pipe and the outside diameter was about the outer size of the donut gasket. It did the job beautifully. I can't provide dimensions because we did it by the "cut a bit and hold it up to the pipe and check the size" method until we had a size that worked. The stock donut gasket perched on that ring very nicely and we got a nice leak tight install.

I expect your idea of cutting down a donut gasket and using the stub of it as a spacer will work well as long as the structure of the gasket can stay intact with the top part missing and being subjected to clamping pressure. I expect/hope it will hold up just fine.

Let us know how your idea works out.
 

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So is there a specific part # that is the correct one?
The improved/corrected version uses the same part number as the earlier one they were selling, I think.

The improved/corrected one has a hangar mounting arm for a rubber exhaust hanger (the same one that the stock Cat hung from) welded to the catalyst canister. The early Magna Flow unit does not have that hangar, the early unit is only supported by the exhaust pipe connections at the pre-cat (exhaust header) flange and at the flange connection to the muffler pipe, no mounting arm welded to the Cat canister. So, you can tell them apart visually.
 

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2zz swap

anyone know if you could modify the magna flow header or downpipes designed for the 1zz to fit the 2zz swap so you can smog in california?
part numbers are 56066 for header and 457065 for downpipes
 

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anyone know if you could modify the magna flow header or downpipes designed for the 1zz to fit the 2zz swap so you can smog in california?
part numbers are 56066 for header and 457065 for downpipes
Not sure about that. Theoretically you can use the 1zz exhaust parts on the 2zz (with modified exhaust manifold flange), but you will only face exhaust restriction. Whether or not that helps the engine pass smog, remains to be seen. The visual part of the inspection, if done by a competent tech, will likely fail.
 

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Has anyone installed the 457065 cat? How's the fitment and install process with this part? Are all of the necessary gaskets provided?

I have the stupid P0136 code and I can hear leaks when I drive. Sounds like the flex joint(s) may be leaking so I'm looking to replace them. I'm going to confirm this weekend when I get the car up on ramps.
 

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Has anyone installed the 457065 cat? How's the fitment and install process with this part? Are all of the necessary gaskets provided?

I have the stupid P0136 code and I can hear leaks when I drive. Sounds like the flex joint(s) may be leaking so I'm looking to replace them. I'm going to confirm this weekend when I get the car up on ramps.
I just got it installed today. Fitment seems good. Came with 3 gaskets, although the gasket to the muffler doesn't fit well and needed to hammer in. The hook for the rubber is too far out which is bending the rubber after hooking the rubber to the car.

The Cat looks smaller than the original Toyota one. I haven't drive enough miles to see if this cat can be efficient enough not to throw a CEL without pre-cats in the header.
 
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