cats or no cats?
Thread Starter
Melting Slicks
Joined: Jul 2006
Posts: 2,151
Likes: 0
From: Strongsville Ohio
cats or no cats?
I have hooker long tubes on their way here tuesday and I ripped off the old system. I have muffler eliminators and stock cats. when the headers go on I am debating going with high flow cats or just no cats at all. I have a 94. Its my third car and I am good with the cops so I dont care about loud. I am concerned with back pressure but not really. Should I leave the cats out or get some high flows? Money is not a concern, I want to do it right but of course I dont want to blow money ya know? So with long tubes and muff elims should I get cats or not?
Le Mans Master
Joined: May 1999
Posts: 6,517
Likes: 1,304
From: Windermere FL
I put the long tubes on my L98 years ago. So the experiences with your LT1 will be different. I ran it with the original cat for quite a while and thought that I could improve things by gutting the main cat. It made it louder, but not horrible. Not a lot of performance gains, but did get a lot of 'sulfur' smell out if it. Also on the L98 one can get the dreaded code 32 from doing this. I did not.
A couple of years ago I took it to a local shop and they converted it to true duals (which I did not have and I put in some modern hi-flow cats. It got quieter as expected, but still sounds very nice. No more sulfur smell. I never really checked to see if I really gained anything or not but I have to believe that getting rid of that gutted old cat can created a lot of turbulence.
As I recall, the whole job was about $500 to convert it to true duals using the Flowmasters I had in there and installing two of the high flow cats.
A couple of years ago I took it to a local shop and they converted it to true duals (which I did not have and I put in some modern hi-flow cats. It got quieter as expected, but still sounds very nice. No more sulfur smell. I never really checked to see if I really gained anything or not but I have to believe that getting rid of that gutted old cat can created a lot of turbulence.
As I recall, the whole job was about $500 to convert it to true duals using the Flowmasters I had in there and installing two of the high flow cats.
Team Owner
Joined: Dec 2000
Posts: 90,675
Likes: 304
From: SE NY
Cruise-In II Veteran
FYI, at say 350chp you need at least 800cfm of exhaust flow to avid a slight power loss due to back pressure, so dual 400cfm cats would be fine.
With good FL headers the "tuning" is done at the collector so you don't need any more back pressure beyond.
If you would like to try open pipes, just install two "test pipes" where cats could be installed later.
With good FL headers the "tuning" is done at the collector so you don't need any more back pressure beyond.
If you would like to try open pipes, just install two "test pipes" where cats could be installed later.
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Instructor
Joined: Apr 2008
Posts: 137
Likes: 1
From: Saratoga Springs NY
I looked at the hooker long tubes, but they are not suppose to fit LT1 cars from what I read, although I am not sure why. What part number did you go with. Let me know if they fit or not when you install them.
Drifting
Joined: Aug 2000
Posts: 1,614
Likes: 0
From: Colleyville Texas
Have the Hooker L98 headers on my 94 LT1 with the car sound high flow cats. They are interchangeable with the off road pipes if I want to take them off.
On my 396, its worth 10-15LBS of low and mid torque without the cats. The noise is loud without the cats but the Power Effects modules can be closed which makes it tolerable.
On my 396, its worth 10-15LBS of low and mid torque without the cats. The noise is loud without the cats but the Power Effects modules can be closed which makes it tolerable.
Burning Brakes
Joined: Oct 2009
Posts: 773
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From: Minneapolis MN
Le Mans Master
Joined: Jun 2009
Posts: 5,060
Likes: 1
From: Tabernacle NJ
St. Jude Donor '10-'11-'12-'13
cat technology is very good these days
Melting Slicks
Joined: Jun 2002
Posts: 2,705
Likes: 30
From: Chesapeake Beach Maryland
2015 C5 of Year Finalist
Thanks.But will getting rid of rear O2 sensor cause running issues(rich,lean)?Will the check engine/service engine soon light be on?I know on OBD 2 it would cause these issues.Do those O2 simulators work properly?Can computer be programed to compinsate with the rear one missing?Sorry to get off topic
As far as cats go. I have the Random Tech cats behind EM Long Tube headers. I went with the cats just to be safe with any potential inspections and to help keep any unfriendly gasses out of the atmosphere. I don't know if that really helps but what the hell. If you don't have emissions I don't know why it would hurt to leave them off. My car is pretty loud with the RT Cats and headers, so if you are afraid of the cats quieting down the exhaust too much, don't worry about that either. I hope you find peace in your decision.
