Catalytic converters?
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From: Rapid City, SD
Car: '83 z/28
Engine: 305
Transmission: T5
Axle/Gears: Stock?
Catalytic converters?
Hi, well I have a 91 T/A L98 N10 (dual cats) car. Well It was suppose to have the dual cats, but now it has some hacked up y-pipe with no cats, well, I am putting in some hedman shorty headers, and need to get a new y-pipe made up. So I am going to put cats back in, to be all legal, and thats the only way an exhaust shop will touch it.
So, my question is, what do you think I should do? Put dual 2.5" high flow cats in? Or, Put a single 3" high flow cat in? The single 3" would be a cheaper way to go, but, I kind of want to run a cat, but I want performance also, I am not in an emissions state, but still am trying to be responsible.
So, my question is, what do you think I should do? Put dual 2.5" high flow cats in? Or, Put a single 3" high flow cat in? The single 3" would be a cheaper way to go, but, I kind of want to run a cat, but I want performance also, I am not in an emissions state, but still am trying to be responsible.
Thread Starter
Senior Member
iTrader: (5)
Joined: Nov 2007
Posts: 529
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From: Rapid City, SD
Car: '83 z/28
Engine: 305
Transmission: T5
Axle/Gears: Stock?
Re: Catalytic converters?
Like I said, an exhaust shop wont touch it, without putting cats on, and I dont mind putting cats on, because hell, these cars are not that fast anyways, and budget, well, one cat or two, that doesnt matter either. I just figure, If i am going to put a cat on, I want the best setup, I know the dual cats, are suppose to be a better way, but that is comparing stock dual cat, to a stock single cat setup, and the stock single cat is alot smaller than the 3" high flow one that I am looking at.
So, it's either (2) 2.5" high flow cats, or.
(1) 3" high flow cat
Joined: Aug 1999
Posts: 19,282
Likes: 103
From: Lawrence, KS
Car: Met. Silver 85 IROC/Sold
Engine: 350 HO Deluxe (350ci/330hp)
Transmission: T-5 (Non-WC)
Axle/Gears: Limited Slip 3.23's
Re: Catalytic converters?
IIRC, Catco makes a dual set-up. Search Summit.
JamesC
JamesC
Joined: Jul 1999
Posts: 10,950
Likes: 26
From: Orange, SoCal
Car: 1990 Pontiac Trans Am
Engine: 355 TPI siamesed runners
Transmission: Tremec T56
Axle/Gears: 12-Bolt 3.73
Re: Catalytic converters?
Get a custom 2.5" mandrel-bent y-pipe with dual 2.5" Magnaflow cats put in. That setup works great for me.
Search the exhaust board for "dyno don headers" and you'll see the pics.
Search the exhaust board for "dyno don headers" and you'll see the pics.
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Joined: Mar 2000
Posts: 43,187
Likes: 42
From: Littleton, CO USA
Car: 82 Berlinetta/57 Bel Air
Engine: L92/LQ4 (both w/4" stroke)
Transmission: 4L80E/4L80E
Axle/Gears: 12B-3.73/9"-3.89
Hedman makes dual cat headers that include the pipes to the cats. Install cats where they're supposed to be, and you're there.
Thread Starter
Senior Member
iTrader: (5)
Joined: Nov 2007
Posts: 529
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From: Rapid City, SD
Car: '83 z/28
Engine: 305
Transmission: T5
Axle/Gears: Stock?
Re: Catalytic converters?

Thanks for you good input guys, I think I will probably do a dual cat setup. But keep the input coming.
Joined: Mar 2000
Posts: 43,187
Likes: 42
From: Littleton, CO USA
Car: 82 Berlinetta/57 Bel Air
Engine: L92/LQ4 (both w/4" stroke)
Transmission: 4L80E/4L80E
Axle/Gears: 12B-3.73/9"-3.89
Probably less than you would pay to have someone fab pipes or modify your existing pipes to fit standard Hedman hedders.
Joined: Jul 1999
Posts: 10,950
Likes: 26
From: Orange, SoCal
Car: 1990 Pontiac Trans Am
Engine: 355 TPI siamesed runners
Transmission: Tremec T56
Axle/Gears: 12-Bolt 3.73
Re: Catalytic converters?
In post #11 he has a pic of his dual cat and single cat y-pipes.
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