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Single Cat vice Duals

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Old Mar 6, 2007 | 09:39 AM
  #1  
lthrneck's Avatar
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From: San Angelo, Texas
Car: 89 Iroc
Engine: 350
Transmission: T56
Axle/Gears: 3.70 9bolt
Single Cat vice Duals

Gents,
I will be coming home to Texas here in a couple of years (retiring from the Marine Corps) and am in the process of purchasing headers for my car. I have an 89 iroc with the dual cat option but I want to go with Hooker/SLP headers and they do not make a dual cat version.

If I convert to a single 3inch cat vice the duals will i be able to pass inspection you think?

If I can't go single cat what did you do as far as headers? I do not want to run LTs since my car is a daily driver and i hate scraping the ground.

I will be lving in the San Angelo area so I will not have to pass the sniff test only the visual I believe?

Thanks in advance
Lthrneck
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Old Mar 6, 2007 | 10:26 AM
  #2  
3.1EyeCandy's Avatar
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From: Conroe, TX
Car: 1987 GTA
Engine: LS1
Transmission: 4L60e
I'm pretty certain that in 89 you could also buy a thirdgen with a single cat - meaning that the inspectors really wouldn't know the difference between your stock equipment and typical stock equipment. As long as you had a Cat they could visually see - I'd venture to say you'd be fine.
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Old Mar 6, 2007 | 02:45 PM
  #3  
Zap Racing's Avatar
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From: Houston Texas
Car: 1989 IROC Z-28
Engine: L98 350--modified
Transmission: 700 R4--modified
Axle/Gears: 4:10 Posi
Where in Texas?

I'm pretty sure U can keep the dual cats--just need some custom pipe bending done. I have seen dual cat systems aplenty--go to the correct tech board here on Thirdgen.org and do a search or 2--U will see threads that deal with this.
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Old Mar 6, 2007 | 05:41 PM
  #4  
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From: Houston
Car: 1992 25th Ann. Z28
Engine: 5.7 TPI - Stock
Transmission: th700 r4
Axle/Gears: 3.23
If it's going to be a while before you get ready for this particular project... keep your eyes open for a complete set of Hooker 2056's. I was lucky and found a brand new set for $200.00 about a year ago. The deals are out there, you just have to have the cash on hand to strike the deal when they come up. Good luck!

Edit:

BTW... found my set on E-Bay

Last edited by hitman; Mar 6, 2007 at 05:43 PM. Reason: add comments
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Old Mar 6, 2007 | 06:37 PM
  #5  
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From: Hou. TX
Car: 86 TA, 91 B4C
Engine: 5.3, 4.8
Transmission: 4L80 4000, T56
Axle/Gears: 4.30 M12, 23.42 10 bolt
You can use a songle 3 inch cat...err you can pay somone if you "know" them...
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Old Mar 7, 2007 | 12:08 AM
  #6  
3.8TransAM's Avatar
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From: Schererville , IN
Car: 91 GTA, 91 Formula, 89 TTA
Engine: all 225+ RWHP
Transmission: all OD
Axle/Gears: Always the good ones
Early 89 had single cat late 89 350 had dual cat.

U can get by with either.

If u have a good 2.5 inch y-pipe or the like the single cat is easier and cheaper and will work just as good.

Plus, u can flange it and make a straight pipe and swap the cat back in for emissions. :-)

later
Jeremy
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Old Mar 15, 2007 | 11:45 PM
  #7  
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From: Magnolia, Tx
Car: 1986 Corvette
Engine: 350
Transmission: T56
Axle/Gears: 3.07
When it turns 20 years old you only have to pass the old 2speed idle test. No more loaded roller test. Most any good running tpi will pass that, 1 cat, 2 cats or no cats. benny
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Old Mar 16, 2007 | 08:02 AM
  #8  
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From: San Angelo, Texas
Car: 89 Iroc
Engine: 350
Transmission: T56
Axle/Gears: 3.70 9bolt
Benny,
I will be going to San Angelo, I don't think they even do emission test just visuals. I am looking at going with the SLP/Hooker headers so looks like I will be converting my exhaust to a high flow single cat. I have the actual dual cat, cat-back (but cats have been removed..bought it that way)system on my car now. I was just thinking that two cats would flow better than one.
Semper Fi
Lthrneck
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Old Mar 16, 2007 | 09:29 AM
  #9  
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From: Houston Texas
Car: 1989 IROC Z-28
Engine: L98 350--modified
Transmission: 700 R4--modified
Axle/Gears: 4:10 Posi
No cats would flow better than 2 cats
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Old Mar 16, 2007 | 10:22 AM
  #10  
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From: Orange, CA
Car: '90 Trans Am-12.45@110.71
Engine: 355 w/AFR 195's Elem. 400/430 HP/TQ
Transmission: Tremec T-56
Axle/Gears: 12 Bolt 3.73
I believe this is simple .....8 cylinders thru 1 cat or 4 cylinders thru each cat...do the math.
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Old Mar 16, 2007 | 08:31 PM
  #11  
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From: houston
Car: 83 POS monte carlo 2015 chevy P/U
Engine: 92 5.7 tpi 5.3
Transmission: 700r4 6L60E
Axle/Gears: 2.42 too high
as far as i know the areas of Texas that have ASM emissions testing only do the 2 speed idle test on rare occasions, such as full time all wheel drive, or with traction control that can't be turned off, some heavy duty applications & maybe some other instances that i haven't seen.. other wise a ASM vehicle
gets ran on the dyno. emissions testing ends when the vehicle hits 25 model years old. this is the last year for ASM testing on 83 models, next year its safety only with visual for emissions parts for an 83.
also, as far as i know all of Texas does visual for all emissions parts, if they don't do the actual emissions tests where your at, you should be fine with empty cats.
something to think about, you can get ticketed for missing emissions parts by a state trooper if they feel like checking, this may also apply to local cops too.
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Old Mar 17, 2007 | 07:55 PM
  #12  
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From: Magnolia, Tx
Car: 1986 Corvette
Engine: 350
Transmission: T56
Axle/Gears: 3.07
Denn,
I don't know the law. The inspector in montgomery county I took my '86 vette to didn't put it on the rollers. Same guy did put my '89 Formula on the rollers. I didn't intend to spread misinformation. benny
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Old Mar 17, 2007 | 10:10 PM
  #13  
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From: houston
Car: 83 POS monte carlo 2015 chevy P/U
Engine: 92 5.7 tpi 5.3
Transmission: 700r4 6L60E
Axle/Gears: 2.42 too high
humm, maybe he or the state thought the vette had traction control or something

no worries, things do change, which is why i said, "as far as i know". i didn't mean it as a dig on you, sorry if you took it that way<me
i was relating what i was told when i took the class to do inspections class 3 years ago.
sometimes it seems no one really knows what the state is doing on emissions, & even sometimes with safety.
this is one of the things i asked about when i took the class, i asked if the drivers door needed to be able to open, they told me if it doesn't, crawl across the seat, 6 months ago my boss was told there had to be 1 working door handle on the drivers door & it must open, but there is nothing about working doors anywhere when we fill in the form in the machine.
when we asked our rep about it, she said she would check, so far she knows nothing about it.

did you know you do not need a drivers seat to pass safety? the inspector can refuse to drive it, but he can not fail it for that. the seat is not required, but you still must have the seat belts properly mounted & in good working condidtion.

on a bit of a side note, if you have a car that passes safety but fails emissions & you are low income, or you have a kid who is 18 or over with a valid Texas drivers licensee & falls under low income, you can get up to $600.00 in repairs paid for by the state under air check. it doesn't matter who's name the car is in, only who brings it in & fills out the paper work.
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Old Mar 17, 2007 | 10:20 PM
  #14  
benny42's Avatar
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From: Magnolia, Tx
Car: 1986 Corvette
Engine: 350
Transmission: T56
Axle/Gears: 3.07
I don't know the inspector. Maybe he did go easy on the vette. Texas has some
odd rules. No seats, but you better have those belts. The vette is due in a couple of weeks, I'll let you you know how it does. benny
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Old Mar 18, 2007 | 07:30 AM
  #15  
lthrneck's Avatar
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From: San Angelo, Texas
Car: 89 Iroc
Engine: 350
Transmission: T56
Axle/Gears: 3.70 9bolt
Dyno,
I was thinking dual cats would flow better as well, the reason I have inquired through PM about your headers. Figured I coule go with yours and build my own Y-Pipe instead of going down to a single cat. Do you think two 2.5 duals would be enough or go 3inch? Please send me a PM back with price.

3.8,
I understand about not having to buy two cats would be cheaper but I think it wold factor out to about the same with me having to change the I"pipe adn all for a dual cat system. Not sure but free flowing dual cats would only be about 100 bucks extra.

Just talked to my brother-in-law and he is adding nitrous to his crapstang so I have to be able to carry some horsepower through the exhaust. I will not allow him to outrun me. (I have more cash than he does)

Thanks for the help guys, this is the best source of knowledge on the internet. IMHO.
Semper
Lthrneck
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Old Jun 9, 2008 | 01:33 PM
  #16  
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From: San Angelo, TX
Car: 1988 Pontiac firebird
Engine: '93 LT1
Transmission: Built 700R4
Axle/Gears: 3.70 9 bolt
Re: Single Cat vice Duals

sorry so late. i haven't ever seen emissions test here in San Angelo, but some places will look under the hood and under the car. i know a handful of places that will only make sure the lights, wipers, and horns work...for us catless cruisers .
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Old Jun 9, 2008 | 02:48 PM
  #17  
dirtywhiteZ28's Avatar
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From: Houston, Texas
Car: 84' Z28-White/T-Tops
Engine: H code LG4 305
Transmission: TH700R4
Axle/Gears: Stock 3.23
Re: Single Cat vice Duals

Originally Posted by DENN_SHAH
on a bit of a side note, if you have a car that passes safetybut fails emissions & you are low income, or you have a kid who is 18 or over with a valid Texas drivers licensee & falls under low income, you can get up to $600.00 in repairs paid for by the state under air check. it doesn't matter who's name the car is in, only who brings it in & fills out the paper work.
The rest of this requirement is that the car has to be registered in the state of Texas for a minimum of 12 months prior to the test, and have passed the test in the prior year. This is supposed to prevent people from using every titled vehicle they can get their hands on from a scrap dealer that was abandoned or otherwise not an actually functioning car prior to the attempted test.
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Old Jun 9, 2008 | 10:58 PM
  #18  
sinisterrs's Avatar
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From: Needville
Car: 1991 Camaro RS
Engine: 305 5.0
Transmission: 700r4
Axle/Gears: 2.73's
Re: Single Cat vice Duals

just like with the drivers seat ... you have to have functioning wipers and in good shape but windshield is not required
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