#1 Member
Join Date: Oct 2001
Location: Appleton, WI. 54914
Posts: 496
Car: 91 Firebird
Engine: L03
Transmission: Auto
Will a 3" cat fit my exhaust?
Probably a very simple question that I may already know the answer to, but my cat is shot and I am thinking of buying Catco's 3" part # CTO-9118. I already had a 3" cat-back exhaust, but stock exhaust manifolds. If I buy the cat will it all fit together properly? Thanks for any help you guys can provide.
#2 Senior Member
Join Date: May 2004
Location: stockton, CA
Posts: 1,396
Car: Camaro RS/SS
Engine: 5.7 LS1
Transmission: 4L60E Transgo shift kit, 3500 stall
Axle/Gears: 4th Gen Rear 3:42
You should be fine. It would be easier if you had 3" pipe which you do. go for it. OR you can go CATLESS....just a thought
__________________
WORD AND YOU KNOW THIS!!!-
Track Time: 12.9@104mph OH YEAH!!! Year: 1989
Make: Chevy
Model: Camaro RS
Powertrain: LS1/4L60E
Rearend: Posi 3:42
Upgrades:
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Transgo Shift Kit
-
Vig 3500 Stall
-
Tranny cooler
-
Cold air intake
#3 Senior Member
Join Date: Oct 2004
Location: Worcester, MA
Posts: 3,361
Car: 86 T/A
Engine: HSR 355
Transmission: 700R4
Axle/Gears: 2.77 posi
Catless until inspection time.
#4 Member
Join Date: Oct 2001
Location: Appleton, WI. 54914
Posts: 496
Car: 91 Firebird
Engine: L03
Transmission: Auto
I would love to go catless but I don't have access to any welding equipment to weld a straight pipe in and there are NO shops willing to cut a cat out around here. Any other ways around it?
#5 Moderator
Join Date: Mar 2000
Location: Littleton, CO USA
Posts: 29,700
Car: 82 Berlinetta(2)/57 Bel Air
Engine: 86 LG4-> ZZ3(LS1)/mild 396
Transmission: TH700(T56)/TH400
Axle/Gears: 3.23(4.10)/3.73
It won't fit without modification to the y-pipe at the cat inlet and the cat-back at the cat outlet. Welding required.
#6 Senior Member
Join Date: May 2004
Location: stockton, CA
Posts: 1,396
Car: Camaro RS/SS
Engine: 5.7 LS1
Transmission: 4L60E Transgo shift kit, 3500 stall
Axle/Gears: 4th Gen Rear 3:42
Are you sure the shops wont do the Catless for you? The shops in Cali will do for me. Huh? Go figure
__________________
WORD AND YOU KNOW THIS!!!-
Track Time: 12.9@104mph OH YEAH!!! Year: 1989
Make: Chevy
Model: Camaro RS
Powertrain: LS1/4L60E
Rearend: Posi 3:42
Upgrades:
-
Transgo Shift Kit
-
Vig 3500 Stall
-
Tranny cooler
-
Cold air intake
#7 Senior Member
Join Date: Oct 2004
Location: Worcester, MA
Posts: 3,361
Car: 86 T/A
Engine: HSR 355
Transmission: 700R4
Axle/Gears: 2.77 posi
Quote:
Originally posted by Ramair21 Are you sure the shops wont do the Catless for you? The shops in Cali will do for me. Huh? Go figure
Its a federal law and $1500 fine as far as I know. A shop breaking the law like that will really get screwed over.
#8 Member
Join Date: Oct 2001
Location: Appleton, WI. 54914
Posts: 496
Car: 91 Firebird
Engine: L03
Transmission: Auto
That's what I was afraid of. Would there be any welding/modifications to make if I also put on new headers/y-pipe?
#9 Moderator
Join Date: Mar 2000
Location: Littleton, CO USA
Posts: 29,700
Car: 82 Berlinetta(2)/57 Bel Air
Engine: 86 LG4-> ZZ3(LS1)/mild 396
Transmission: TH700(T56)/TH400
Axle/Gears: 3.23(4.10)/3.73
If you get emissions-legal headers intended for '86-'90 TPI single cat application, such as Hooker 2055, the 9118 cat will slip onto the y-pipe and you can clamp it together if you like.
#10 Senior Member
Join Date: Mar 2003
Location: Florida
Posts: 3,411
Car: 1987 Black IROC-Z (original owner)
Engine: 350 Crate with TPI
Transmission: 700R4 with 2400 SLP Stall
That Catco part number was made for a stock application.
#11 Senior Member
Join Date: Jun 2001
Location: DC Metro Area
Posts: 5,504
Car: 87TA 87Formula 97TA 92K1500Blazer
It really depends on the car, there have been at least 6 different cat setups on the V8 3rd gens, and some years had 2 or 3 possible setups. In most cases on a V8 car you’ll have either a 2.5 or 3” cat, but in some cases it might be flanged or you might have dual cats
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