ItalianZ32

I currently have hedman headers going to the stock converter and then to a 3" borla exhaust. I was looking into high flow catalytic converters and i was just wondering if anyone has any experience with certain ones.

I was leaning towards the Random Technology 3" high flow cat, but i wanted to get other opinions first. Thanks.

84 z28

I you want an opinion I go by"no converter is a good converter"

slow_90firebird

People on my last car forum had good luck with random tech. They are supposed to make a real nice cat.

Little too high priced for my blood, though.

ItalianZ32

They are a little high priced, but I just don't know what else to get. Can I get just about any 3" cat? I mean the Random Technology one is supposed to be a direct fit for my setup, so I figured it would be easier, but if I can use a pacesetter cat I wouldn't mind doing that.

slow_90firebird

Magnagflow and catco both offer them too...

ryan91rs

iTrader: (1)

depends you need to be careful to get one with the air inlet if you want to keep the same emissions set up. I went without one and it was not ideal. Had a few issues.

Kevin91Z

iTrader: (1)

I always recommend Magnaflow. I've had no problems with them.

enoughtraction

recomendation:
step 1: remove smog pump if applicable
step 2: change to headers
step 3: replace cat with test pipe
step 4:

Kevin91Z

iTrader: (1)

Step 1 and Step 3 are illegal on a street car in all 50 states, thanks to federal EPA laws. Keep your emissions stuff on, its not hurting anything and its helping to keep the air you breathe cleaner.

327_TPI_77_Maro

iTrader: (8)

Yeah there is no reason to delete the cat, especially on a 305 car. A 305 car is not built for speed in the first place, so you are not hurting anything keeping it cleaner burning.

Most of the cats are the same type of brick element, so one is probably not going to flow any better than another. The only exception is that some of the higher end cats are now a different spun metal element inside that is supposed to flow better than the traditional honeycomb.

Shadowman

I agree with EnoughTraction. Ditch the smog crap, unless your area does VET.

ChillPhatCat

On a semi-related note... My car has no smog pump and no lines for a smog pump. The previous owner blocked off the air tube at the cat.

Now, I need to get the thing to pass inspection by next Jan. or I can't renew my registration. I basically need to make it look like the car didn't come with an air tube to the cat in order for it to pass. What is the possible harm if any to the cat if I run a cat without an air tube in place of the original cat that had one? State regulations state specifically that there has to be a Cat and a PCV valve... without an emissions sticker, that's all they will check for.

84 z28

In NY state well atleast in Rochester. Any car that is 26 years old has no emissions checks just safety checks. It would pass if he had a 1982.

ChillPhatCat

Though... it is still illegal to remove the emissions equipment that came on the car. It's just not something they check for on cars that old, so you can basically do whatever you want... just don't expect a legitimate shop to remove cats from your car or anything like that.

brandotron

iTrader: (2)

I've had good luck with Magnaflow too.

Kevin91Z

iTrader: (1)

Federal law trumps state law. Federal law says you cannot remove any emissions equipment on a street car. End of story. But if your state doesnt check for it, there's not much to stop you. Just keep in mind that more and more states are starting emissions checks and will be looking for this stuff.

enoughtraction

unless they actualy put a hose on your exhaust than it doesnt matter the car isnt old enough to hook an obd2 comuputer to, the smog pump is a joke and a real good working cat is very expensive, im not sure about anywhere else but i live in nh in the summer and florida in the winter neither place does any emissions testing on vehicles this old(but i know other places do) and also emissions from an engine are negligable unless your running rich or lean anyway (worry about nitrides of oxygen not co or co2 as it can react with ozone and make it exponensial worse and except for those three things and a couple things that are still present in very minute amounts most of your exhaust is water oxygen hydrogen etc etc)if you need to pass emissions in your state and you want power go with a really good free flowing cat the magnaflow should be good and isnt INSANELY expensive and TRY to pass with the smog pump disconnected if it fails put the belt back on for the test if it passes you can change to headers, and the smog pump will rob hp and torque...it creates a fair amount of drag. it really just matters how they test in your state. if your worried about co2 plant a tree they turn it into o2 lol

ChillPhatCat

Funny thing is, it's actually illegal to put a cat on a car that didn't come with one the way the law is written.

IROC-Z_Racing

iTrader: (1)

I live in NC and my 89 IROC is not emissions inspected, BUT NC inspection laws state that if it came on there from factory, it MUST BE ON THERE NOW and they visually inspect to see if there has been any tampering with the emissions system. I hate that. Does anoybody that lives in NC able to remove that cat or know of a away to get by some of these stupid restrictions without getting caught?

If not, what cat flows pretty good, is a descent price and gives the exhaust a nice rumble instead of a raspy popping noise? My setup is a true dual with pypes driveshaft tunnel x-pipe and 18" sweet thunder chambered mufflers.

Thanks,
- Justin

Rayzor32

iTrader: (1)

the best catallac convertor is a straight pipe. i always cut them ****ers off all it does is rob horsepower plus u can scrap them and get mad money for em.
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Dont waste ur money on a cat man even the hi flo ones once they get used they dont flo good no more ne way. Yo listen heres wut u do:

ur gonna GUT the CAT, meaning take a BFScrewdriver and smash the honeycomb crap out, after that u can leave it like that OR (this is the better way) find a pipe thatll fit in there good so its just like running a straight pipe with a CAT casing over it. It also pays to no ppl who can do inspections. Or if u can find a guy with stickers or a car u could pull one off of

Rayzor32

iTrader: (1)

In Buffalo its any car before 1996.

ChillPhatCat

All of upstate NY is the same. 1996 is just the cutoff for the OBDII check, they still do a visual check on emissions equipment... you will not pass without a cat anywhere in NY on a car made in the last 25 years.

slow_90firebird

So just tack weld a set of old heat shields onto a test pipe with an air tube...

ChillPhatCat

'Cuz that's a lot easier than using a real cat and allowing the loss of 1 Hp.

Rayzor32

iTrader: (1)

things arent so strict in buffalo i no alotta ppl who work in garages and they aint gonna fail u for not having a cat. I no plenty of cars that dont got cats on em. And u lose a lot more than 1hp, an old *** stock converter dont flow **** compared to a 3" straight pipe. u rnt gonna get in trouble maybe in california u would but not in wny. If ur worried u could try wut he said with the heat shields. the ONLY emmisons tests is done on 96 and up cars with OBDII anything else is just visuals. I dont no about other counties. I mean just because its 'illegal' alotta ppl do it neway and u gain horsepower so why not. They can fail u for compression fittings on brake lines too but those work fine, ny state just does a lotta stupid ****.

ChillPhatCat

Some shops operate above the law... that doesn't mean you can run without cats and expect to pass inspection at any place. Any legitimate shop will fail you for a lack of cat, pcv and compression fittings on the brake line... along with a myriad of other things.

It's easier to run a cat and the power argument is silly because high flow cats barely impede exhaust flow. Also, I wouldn't want to trust my life on compression fittings. Run a cat, save a tree, give up a horse.

enoughtraction

didnt mean it was legal just like you said, if they dont test they wont ever know, i mean its not like the cops check out your car if your pulled over, maybe if like....you got it impounded or something but youd have to be like trying to see what your top speed is on the highway and getting caught? or 90 in a 30 or something lol

Rayzor32

iTrader: (1)

exactly man, and if your car did have a cat in it when it goes to the impound lot it probably wont have one when it comes out

Kevin91Z

iTrader: (1)

The smog pump is just a pulley with an offset weight on it that pushes air, kinda like a fan. Its not sucking more than 3-4 horsepower, same as a high-flow catalytic converter. Nobody here is butt-dyno sensitive enough to notice it, and its a couple hundredths in your timeslip, if that.

I'm trying to help you guys. The more of you that get caught removing your emissions devices, the more the hippies and the politicians are going to write new laws to make the restrictions tougher and the fines higher. Several states that didnt use to have emissions tests are now getting them, such as Florida. Please be a responsible hot-rodder and show the ignorant politicians that we're not just a bunch of dumb red neck hillbillies with cars that get 5 miles per gallon and pollute black smoke.

Fyrstorm

iTrader: (1)

Amen.

Uglybronco

iTrader: (2)

Wow, you people need to stop bangin your cousins and start a new thread titled "Catalytic Converter Bashing" This thread is supposed to be finding out about the ups & downs of different brands of cats versus one another, not versus straight pipes. But since this thread is so far off topic now:
Don't new converters have a 3rd element that does not reqire the air pump? I know my '03 Chevy has two 3" cats and no tubes running to them, no tubes running to the manifolds and no air pump... Also my dad's '89 1 ton had the exhaust replaced and the new cat had a tube coming out but they just capped it because there was nothing to hook it to. (Also note I live in an emissions testing area...)

Back on topic: What 2-1/2 or 3" Cats are decently cheap and are small enough so I could fit two under my firebird?

dirtywhiteZ28

A lot of the newer cars do have a smog pump, its typically electric and they stuff them in the front bumper cover. That way, when you hit a Texas sized racoon on the toll road or the neighbors poddle, at 2:30 am, you get to replace it along with the bumper cover.

ChillPhatCat

IMO Catco is one of the best values out there, there's a number of universal cats in 2.5-3" they sell for under $70 from 12"-16" in length.

327_TPI_77_Maro

iTrader: (8)

This is probably the most ethically responsible post I have ever seen on a car message board. All these guys that want to hack off their catalytic converters so their car can run a 16.99 in the 1/4 instead of a 17.00 are just perpetuating the gross polluter stereotype of hot rodders, and its just going to end up biting us all in the ****. The days of "hack off the emissions equipment because I don't know how it works and I dont' know any better" SHOULD be over.

ItalianZ32

Exactly, I was just trying to find a good quality catalytic converter. Right now I have headers with a 3" y pipe, down to a stock cat (2 1/4" or 2 1/2", not really sure) and then back to a 3" exhaust. I want to keep it in line with emissions in CT and just get a little better flow. Right now I am leaning towards magnaflow, but I am also looking into the catco as well, since I have seen some good posts about that one as well. Thanks for all the help!

327_TPI_77_Maro

iTrader: (8)

How do you have a 2.25" or 2.5" cat with a 3" exhaust? How does it even bolt up?

dirtywhiteZ28

Has any one tried the Edelbrock headers that summit has,supposedly they have all the factory conectors and A.I.R. tubes. I know it seems that Edelbrock doesn't like making parts that only fit third gens but.....
If the guy already has the smog stuff off I would recomend buying a Cat that has no AIR tube in it, that way you don't have to worry about it restricting nor deflecting the exhuast any more than whats going to happen from the brick. Also pull that old one out and measure the ID/OD of both inlet and outlet, along with the overall length. Then call the guys at Summit techline, they can sort thru the unpublished list of exact deminsions faster.
By the way I had a Borla Cat Back on my '97 Z28, a 2x4 took out my cat and I replaced it with a Random Tech, and was really happy with it.

ItalianZ32

The mechanic fit a pipe from the header to the front of the cat that starts at 3" and then goes down to 2 1/2" and then again after the cat to the exhaust. I wish I had just changed the cat right when I had the headers and exhaust put on instead of having it the way it is.
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My headers supposively have all of the emissions equipment in them because I made sure to buy the ones that did.

dirtywhiteZ28

Are the size adapters about 4-5 inches long? If so measure what's needed to bridge the gap with the adapters removed, some of the univesal cats are sold in really long lengths.

slow_90firebird

There is only 2 reasons I want to get rid of the catalytic convertor:

- It makes the car sound 100x better with any muffler

- It makes the exhaust smell really nice, like a muscle car should

Not because I want to be a dumb red neck hillbilly

Uglybronco

iTrader: (2)

There are these little things called adapters out there in the world. They make them for pretty much anything round. Or if you wanna go real cheap N dumb you could just put one inside the other and weld 'em up.

If they have the little tubes coming off of them like your manifolds did then yes. I think thats all there is to 'em...

ItalianZ32

I am not sure about how long the adapters are, but I will definately get under there and measure it up before I purchase anything. I would definately say that they are no longer than 4 to 5" though, just not sure exactly.

Rayzor32

iTrader: (1)

All good reasons but you forgot the most important one MORE HORSEPOWER!!! All that smog stuff is useless if u ask me all it does is rob horsepower i dont care what any hippie from california says otherwise.

dirtywhiteZ28

Well while your there look to see if they are welded in or clamped on. Either way you can get adapters in an incredible combination of sizes, including 3"ID-3"ID if thats what you need. They cost anywhere from $4 each up to about $16 each depending on where you go and what size they are. My experience has been that O'Riellys was the best price for these. Auto Zone was consistantly a minimum $1 more for the same size adapters, but even Auto Zone changes its part prices from store to store in the same town. They even have short 6"-8" lengthes of pipe if cutting out the old cat creates to big of a resonable gap.

Kevin91Z

iTrader: (1)

Edelbrock headers stink! Get Hooker 2055's or get some of Dyno Don's headers.

Car sound is in the opinion of the listener. Some people think a gutted cat sounds hollow or raspy.
Raw fuel and exhaust does NOT smell nice. You must have been sniffing too much of it if you think it smells nice.

You're dreaming if you think you're going to notice the difference in horsepower from having a cat in your exhaust or not. Yes, the stock cats from the 80's are horrible and yes they will rob some power. But today's aftermarket cats are all "high-flow" and they do very little to get in the way of power. In fact, depending on the rest of your exhaust you might even gain a little bit of torque below 3000 rpms, but you wont notice it except on a dyno. Same as removing a high-flow cat, you wont notice it except on a dyno, 2 or 3 horsepower at peak.
You can call me a goodie-two-shoes, or a square, or a nerd, but I'm not even close to a hippie. A hippie wouldnt drive, modify, and race a thirdgen.

Magnaflow, Catco, and Random Technology all make good "high-flow" cats. I prefer Magnaflow because they are 10 minutes from me and my father has known the owner for 25 years.

Vanilla Sky

iTrader: (1)

I'm agreeing with the "keep the cat" people.

Everyone should read the current Grassroots Motorsports magazine. There's an article about catalytic converters in there. Pretty enlightening.

And I don't have a problem with states crushing cars that have had their emissions devices that ~work~ removed (the AIR system is useless with a new cat). EGR and PCV can BOOST HP if used correctly.

Rayzor32

iTrader: (1)

yous can go ahead and keep it ill just see yous in my rearview

327_TPI_77_Maro

iTrader: (8)

I understand that adapters are available. I didn't think anyone in their right mind would reduce the size coming off the Y pipe DOWN to a smaller cat. That is the worst setup ever and it needs to come off.

Vanilla Sky, I did a search for monolithic catalytic converters and AIR injection, and it looks like AIR still has a benefit with modern converters.

Vanilla Sky

iTrader: (1)

Fine, let's build identical cars and let robots drive them. The only difference we'll have is the cat. The ONLY thing that will make the one with a cat ANY slower is the weight of the catalyst material.

Idiots need to pull their heads out of their tailpipes.

Rayzor32

iTrader: (1)

dont ****in tell me to get my head outta tailpipes mother****er your ****ing retarded if you think a cat isnt going to affect flow r u ****ing kidding me ur a dumbshit like a said leave your cat on and go slow ill take mine off and have performance exhaust AND scrap it for ~$40 and not waste 120 dollars on a "hi flow" cat thats only going to be "hi flow" for a year or so till it gets dirty then will flow like crap yous can keep thinkin what you want but your a ****in ****