Magnaflow CA Legal CAT: More Power? Nicer Sound? Less Heat?

[Connor280ZX]

Looking into a better CAT that will get me a bit more power, and maybe a nicer sound. Looking at the Direct Fit Magnaflow CAT (CA Legal), on ebay of course. I'm wondering if this CAT will do me any better than my factory one. I'm trying to squeeze every but of power out of my 82 ZX with it still being able to pass smog. The Sellers company has a money back guarentee that this thing will fit, but what do you guys think? Here's the link incase anyone's curious. http://www.ebay.com/itm/290994264987?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649

 

As far as the entire exhaust on my car goes, stock headers, MSA Catback 2.5 Exhaust with a Hooker Headers Muffler.

[BluDestiny]

No you won't really see much gain. I also doubt it will fit. 

[randy 77zt]

Because of california law changes the cat has to be the correct part # for the car per the cat manufacture's specs.California legal cats have numbers stamped into them for id.That cat you have a link to would pass inspection but I would doubt its flow capabilities.If your current cat is working I would leave it alone.I used to have 2 exhaust systems that bolted onto the flange of the turbo downpipe on my 77 .1 was a 2.5" system with a cat and no muffler.The other was a 3" mandrel bend system with no cat and a 3" magnaflow where the cat was mounted.

[Connor280ZX]

Because of california law changes the cat has to be the correct part # for the car per the cat manufacture's specs.California legal cats have numbers stamped into them for id.That cat you have a link to would pass inspection but I would doubt its flow capabilities.If your current cat is working I would leave it alone.I used to have 2 exhaust systems that bolted onto the flange of the turbo downpipe on my 77 .1 was a 2.5" system with a cat and no muffler.The other was a 3" mandrel bend system with no cat and a 3" magnaflow where the cat was mounted.

 

I have a gasket leak back there that should be fixed. Thought i'd get a better CAT while im at it to bring out the full potential of the MSA exhaust. You guys don't think this "Maximum Flow" Converter is any good? I'm not looking for a huge improvement, just a little more flow, and hopefully less heat. This CAT has the honey comb type internals, Versus the stock CAT is a bead type isnt it?

Edited October 31, 2013 by Connor280ZX

[randy 77zt]

I checked the link you posted for the application chart for the cat you listed and the app shows that it fits a bunch of 4 cylinder cars.You would need to do some research on that cat to see what the id of the pipe is on that cat.Its probably 2" or 2.25".If you put a cat that is too large for the engine the cat wont hold enough heat to function-or too small and you get flow restriction.The stock datsun cat is a honeycomb -I have have gutted them before.I would have a muffler shop build a cat test pipe and just bolt the stock cat back in for smog test day.

[rejracer]

To my recollection the stock N/A cat is smaller than the Cat used on the turbo's, 300zx's and Maxima's.  The stock Turbo cat has an inlet of around 2.75", where I think the N/A cat is 2".  If you are going to upgrade, you will need to upgrade the entire system. 

 

What Randy said above is true, you can go too big.  If your car is mostly stock, you will see very little gain, or a net loss in swapping out the stock cat.  You need to know how much flow your exhaust is flowing, and then find a system (not just a cat) that will augment power in that range.  In my opinion 2.5" is a bit on the large side for a stock n/a motor.  Increase power on the stock motor, and it's just right. 

 

The aftermarket cats are notorious for being terrible.  A good quality catalytic converter has about 200 bucks worth of precious metals in it, which is why the aftermarket cats do not work well, or last long.  If you were to replace the cat I would look at a good factory replacement, not an ebay special.  You can get a good used cat for less.  If you are worried about legality, well then that is another can of worms as California smog laws are counter productive at accomplishing what they were intended to do in the first place.  If you want legal, keep it stock.  If you want to meet the intent of the law go with a larger OEM Cat.  if you don't care about either get a hollowed out  cat and weld exhaust pipe through the middle of it for the stealth cat delete or just fab up a cat delete pipe, and put in a cat every 2 years. 

 

I personally would go with a larger quality cat, it's cheaper, and functional. 

[Connor280ZX]

I currently have a cat back exhaust on the car (2.5") but headers are illegal here in CA. Do any of you guys have a recommendation for a higher flowing cat? Or reliable brand?

[randy 77zt]

http://www.magnaflow.com/02catalytic_converters/04basics/04california.asp     From how I interpret the law you have to replace with a part # that the cat manufacture says fits your car.you cant weld in a bigger diameter cat.I would just have some flanges welded to a piece of pipe and put the stock cat back in at smog time.If a smog inspector sees a new cat he is supposed to check to see if its correct for the car.I have a neighbor with a 2004 Mini and the cali legal cat is like $1100 .Bar is sending inspectors to muffler shops to make sure the laws are enforced.

[Connor280ZX]

http://www.magnaflow.com/02catalytic_converters/04basics/04california.asp     From how I interpret the law you have to replace with a part # that the cat manufacture says fits your car.you cant weld in a bigger diameter cat.I would just have some flanges welded to a piece of pipe and put the stock cat back in at smog time.If a smog inspector sees a new cat he is supposed to check to see if its correct for the car.I have a neighbor with a 2004 Mini and the cali legal cat is like $1100 .Bar is sending inspectors to muffler shops to make sure the laws are enforced.

Thats nuts. California is such a bad place for a high performance car, ha.

Anyways, i guess im going to take up the idea of a stealth-cat instead of buying a cat, just to hope itll get me a few more HP. How hard is it to gut a cat? Can it be done without taking it to a shop(Don't want any EPA freaks that might be present to get all nosey on me, and risk a fine)? What about the 49-state cats? Do they flow better?

[randy 77zt]

I wouldnt gut the stock cat.If the cat manufactures quit listing an app for your car and you need i you will be out of luck .If you replace the cat with a 49 state cat it will not have the bar exemption# on it.If the inspector catches it its auto-fail.Just build a test pipe.If you want to get mid-evil on your cat just get a heavy hammmer and a pointy piece of rebar.I am lucky I havent died from exposure to good stuff like cat convertor guts.But that was before I had a smog license.

[Connor280ZX]

I wouldnt gut the stock cat.If the cat manufactures quit listing an app for your car and you need i you will be out of luck .If you replace the cat with a 49 state cat it will not have the bar exemption# on it.If the inspector catches it its auto-fail.Just build a test pipe.If you want to get mid-evil on your cat just get a heavy hammmer and a pointy piece of rebar.I am lucky I havent died from exposure to good stuff like cat convertor guts.But that was before I had a smog license.

I believe MSA sells test pipes, but you have to call them so they can build one for you. What i meant by geting a 49 state cat was: IF a 49 state cat provides better flow, id buy one, install it, and swap it out with my factory cat every two years when i need to smog the car.

[randy 77zt]

Cat convertors in those days were meant to be a mop-up device incase the engine wasnt tuned correctly( ex-bad plug wire-engine miss).I have seen cars with hollowed out cats pass a smog inspection.The engine was in a very good state of tune but the readings were a little high on CO and unburnt HC.Ideally all fuel is burned before it hits the cat-if not you are not getting your money's worth on the gasoline you paid for.If a car is run too long in a missfire condition the cat overheats and melts internally.All of the smog control systems were basically a band-aid added to an existing design of engine.A modern dohc engine can run on a much leaner mix .If you found any old zx's in other states they probably have a piece of pipe welded in place of a cat.As long as the engine is operating as it was when it was new you probably wont make anymore power out of it.Its is operating on a fixed program loaded into the ecm.If you wired up something like an innovate wide band o2 sensor you could see the actual running a/f ratio to see if the efi was programmed correctly.Or put the car on a chassis dyno.I am guessing about 150 rwhp.

[Connor280ZX]

Cat convertors in those days were meant to be a mop-up device incase the engine wasnt tuned correctly( ex-bad plug wire-engine miss).I have seen cars with hollowed out cats pass a smog inspection.The engine was in a very good state of tune but the readings were a little high on CO and unburnt HC.Ideally all fuel is burned before it hits the cat-if not you are not getting your money's worth on the gasoline you paid for.If a car is run too long in a missfire condition the cat overheats and melts internally.All of the smog control systems were basically a band-aid added to an existing design of engine.A modern dohc engine can run on a much leaner mix .If you found any old zx's in other states they probably have a piece of pipe welded in place of a cat.As long as the engine is operating as it was when it was new you probably wont make anymore power out of it.Its is operating on a fixed program loaded into the ecm.If you wired up something like an innovate wide band o2 sensor you could see the actual running a/f ratio to see if the efi was programmed correctly.Or put the car on a chassis dyno.I am guessing about 150 rwhp.

Interesting. I bought my car with a brutal misfire (Due to broken dizzy and bad IACV) which the previous owner wasnt aware of, so my cat might not be in the best shape anyways... It still doesnt run perfect, but i got the misfire problem worked out. Still idles rough, but oh well.  I went ahead and ordered a Magnaflow 49-state cat from Summit Racing. its got 2" internals, and it 13.25 inches long, which supossively is the right lenth. Hopefully it works out. Going to save the old cat, and clean it out before the next SMOG test. I've been thinking about EFI tuning latley, what would it take to hook up a wideband?

[randy 77zt]

A 2" cat is a waste of time and be a restriction.If you are serious about having a known good cat for smog test day I would get a cali legal cat and only install it for test day.Gut the old 1 and reinstall.I would guess that the oem cat id is bigger than 2".I had a 77 280 for years that i played with.I installed new( not cheesy reman) injectors,injector connector plugs,and built a new distributor from 2 with a custom advance curve.Then gutted the cat and put on a custom 2.5' exhaust.Remember back in the day the gasoline didnt have injector cleaner in it.If you have 1 or 2 injectors flowing max 70% the engine will run ok but not make max designed hp.If you put a 2.5 exhaust system behind a 2" cat is that 2.5 exhaust doing any good?You could change exhaust systems and rerun on a dyno all day and never see a single hp gain.What size pipe is before the cat?That should be the minimum size pipe for the whole system including the cat.Making hp isnt about buying shiny stuff.About a wide band-the innoavte unit has 2 outputs-1 for the gauge and 1 for the ecm.the ecm output can be reprogrammed to output voltage of an old narrowband.

[Connor280ZX]

A 2" cat is a waste of time and be a restriction.If you are serious about having a known good cat for smog test day I would get a cali legal cat and only install it for test day.Gut the old 1 and reinstall.I would guess that the oem cat id is bigger than 2".I had a 77 280 for years that i played with.I installed new( not cheesy reman) injectors,injector connector plugs,and built a new distributor from 2 with a custom advance curve.Then gutted the cat and put on a custom 2.5' exhaust.Remember back in the day the gasoline didnt have injector cleaner in it.If you have 1 or 2 injectors flowing max 70% the engine will run ok but not make max designed hp.If you put a 2.5 exhaust system behind a 2" cat is that 2.5 exhaust doing any good?You could change exhaust systems and rerun on a dyno all day and never see a single hp gain.What size pipe is before the cat?That should be the minimum size pipe for the whole system including the cat.Making hp isnt about buying shiny stuff.About a wide band-the innoavte unit has 2 outputs-1 for the gauge and 1 for the ecm.the ecm output can be reprogrammed to output voltage of an old narrowband.

Thats a very good point Randy, however, i made a mistake on my order which i cancelled. I had a funny feeling about the cat i bought (Not sure why i didnt do it to begin with, amatuer mistake) so i went under my car and measured the length of my cat. The lengths were different, so i quickly got back on ebay and cancelled my order. Found the correct one this time which is a bit longer, and has a 2.4' inlet/outlet. Not sure about the stock header. Its either 2.25, or 2.5.

[Connor280ZX]

Alright, just got the cat, and installed it. The exhaust seems to open up more under load, and it does feel slightly quicker. The stock cat was 2.0 inches in pipe diameter, so I definitely have more flow now with the ID of the new cat being 2.25 inches. The header pipe is 2.25 inches as well.

[johnc]

Catalytic converters are not the big exhaust restriction that people think they are. In back to back testing on a Solo2 BMW (STX class) the addition or removal of the cats had no effect on performance. That's on a properly tuned and well maintained car. Andy Hollis found the same results when testing on a STS Miata. The muffler has a bigger impact then the cat (or lack thereof).

[Tony D]

You know they burned witches at the stake in Europe John...

Don't mess with people's religions, they get testy!

[cockerstar]

Slight digression here, but does anyone have any experience with the longevity of the magnaflow cats? Considering one as a stock replacement for one of my non-z cars. Not as a performance part, but to replace the stocker that has gone south (230k miles on the clock). I'm not expecting to get another 200k miles out of it, but if the magnaflow will last until 300k with the engine in good working order, then they're money well spent!

[randy 77zt]

Cat life depends on the engine tune.If you burn the fuel in the engine the cat will last a long time.