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  1. #1

    Default Catalytic Converter Help!

    So I ordered two magnaflow performance catalytic converters the other day. i went to 2 local muffler shops today and the first one said that I ordered the wrong ones and the second one said that the 06 Silverado has the best performance cats on the market. Soooo I have two questions: Will putting a "pre OBDII" cat in my truck make it run bad or just run codes? and is it true that GM's cat is the most high flow cat available?
    Also, JEGS told me the cat would work on my truck, it didn't say that is was pre OBDII in the catalog. It says that is is OBDII complaint. The box for the cat is pre obdII. It makes me mad that now I have to pay for shipping so I can return them.

    Another question, do high flow cats really do that much because i was thinking about ordering another set for Dynatech but if its not gonna make my truck sound any louder or get any quicker there is no point.

    Thanks,
    Chad.
    '07 Chevy Silverado Classic

    PERFORMANCE
    -K&N Intake
    -Air Raid Throttle Body Spacer
    -Thrush Muffler
    -Bully Dog Triple GT Programmer
    5.3L V8
    LOOKS
    -3" Spindle Lift
    -Tint
    -Blacked Out Rims
    -Blacked Out Taillights
    SOUND
    -2 Kicker CVT 12s
    -Rockford Fosgate 6.5"
    -500 Alpine Mono Block
    -Pioneer 6.5" Touch Screen
    -2 Boss Tweeters
    SOON!
    -3.73 gears

  2. #2

    Default

    ...
    Quote Originally Posted by Chad513 View Post
    So I ordered two magnaflow performance catalytic converters the other day. i went to 2 local muffler shops today and the first one said that I ordered the wrong ones and the second one said that the 06 Silverado has the best performance cats on the market. Soooo I have two questions: Will putting a "pre OBDII" cat in my truck make it run bad or just run codes? and is it true that GM's cat is the most high flow cat available?
    Also, JEGS told me the cat would work on my truck, it didn't say that is was pre OBDII in the catalog. It says that is is OBDII complaint. The box for the cat is pre obdII. It makes me mad that now I have to pay for shipping so I can return them.

    Another question, do high flow cats really do that much because i was thinking about ordering another set for Dynatech but if its not gonna make my truck sound any louder or get any quicker there is no point.

    Thanks,
    Chad.
    The Late Model Factory G.M./Chevy Catalytic Converters.......Flow Much Better than Most think they do......unless your Factory G.M./Chevy Catalytic Converter's are going Out/Bad......there's no reason to replace them for aftermarket Cats.......and I have not seen any kind of Dyno Number's showing any big gains with Aftermarket Cats being installed......
    Last edited by 99'HEARTBEAT; 11-14-2011 at 06:58 PM. Reason: Added Infor.

    MIKE


    99"SILVERADO
    5.3 l 3.73 l G80
    BLACK BEAR CUSTOM TUNE
    SNUGTOP l COLORMATCH l KATZKIN










  3. #3

    Default

    X2 what Mike said.
    :cool:

    2005 Chevy Silverado Z71 Crew Cab
    6" Skyjacker lift w/Edlebrock dual front remote resoviour shocks, single rear remote. Rancho skid-plate.
    17" x 9" M/T Classic Lock Wheels, 35" BFG A/T or M/T tires
    4.10 PercisionGears w/factory locker, T/A Performance rear-end cover
    Banks CAI intake, ported throttlebody, JBA coated headers, over-sized Magnaflow cats, Magnaflow cat back exhaust, Diablo tuned
    B&M aluminum deep transmission pan
    Warn brush guard w/Warn 9.5 XP winch, PIAA bulbs, Line-X bedliner, AWS Black tool chest, Extang tonneau cover
    Weather Tech floor mats
    Cover-Craft seat covers
    Dash mat cover
    Formula One window tint
    One black Lab in rear seat.
    :glasses:

  4. #4

    Default

    Replace the plugged cats with High-Flow cats, i convinced my father to do this on his 2000 silverado, and it doesn't downshift nearly as much going on the highway. He said he got a 1-2 mpg increase from going from the plugged to the highflows. Costed him $100 at the muffler shop.
    www.youtube.com/ippielb
    2002 Chevrolet Silverado 1500 z71 1985 Chevrolet Silverado k10 2006 Chevrolet Silverado 2500hd 6.6l LLY Duramax
    6.5" BDS Suspension Lift Edelbrock Carb & Polished Intake Manifold & Valve Covers NAPC Race Transmission & NAPC Built Transfer Case
    EFI Live Comp Cam and Valvetrain Snow Performance Methanol Injection
    35" Toyo Open Country Mud Terrain on 18" Ion Alloy 179's Headman Long Tube Headers and True Dual Exhaust FASS 150gph Titanium Series Pump
    AirAid Cold Air Intake with K&N Dry Filter & AirAid PowerAid Throttle Body Spacer 2" Suspension Lift 33x12.50r15 Tires EFI Live & AFE Stage 2 Intake
    Pacesetter Long Tube Headers with Cats Gone True Dual Exhaust FlowPro 3.73 Gears Yukon Grizzly Locker with Mag-Hytec Cover & Traction Bars
    NGK Iridium Tips & MSD Ignition Plug Wires Baja Spare Tire Holder 33x13.5 Hankook rt03 18" XD Rims
    Innovate LC-1 Wideband o2 Sensor x2 HID's all around LED taillights and 3rd brake light
    BDS Dual Steering Stabilizers Pioneer Double-DIN Touchscreen Navigation with Two 10" Subs under rear seat
    Electric Fan Autometer Pressure, Boost, and Pyro Gauges
    4.56 Gears Airlift Air Bag Suspension

  5. #5

    Default

    Quote Originally Posted by ippielb View Post
    Replace the plugged cats with High-Flow cats, i convinced my father to do this on his 2000 silverado, and it doesn't downshift nearly as much going on the highway. He said he got a 1-2 mpg increase from going from the plugged to the highflows. Costed him $100 at the muffler shop.
    What brands are out there for high flow cats? I am the second owner, and as far as I know the cats on my 04 silverado are up around 100k miles. I don't have any maintenance documentation to prove otherwise.
    2006 Magnetic Black 350Z

    2004 Silverado Z71
    Nitto Terra Grapplers | Viper Remote Start

  6. #6

    Default

    Hi, Chad513:

    Like the first post indicated, it is my opinion that as you get into newer vehicles, which I will define loosely as after 1995, the OEM catalytic converter is going to be increasingly more efficient at allowing pass through at a lower pressure than the predecessors. And aftermarket units made for your vehicle have to comply with specifications that I don't think allow them to do much about what back pressure is created.

    Again like the first post said, and I heartily agree, if your cat is not malfunctioning, don't replace it and don't blame it for any issue you have with "not enough noise". You can remedy that with the right muffler. Personally, I don't want too much noise. Just a nice rumble.
    1994 Chevy K2500 Silverado, 454 (modified), original owner.
    And other vehicles and toys.

    "...If you can meet with triumph and disaster
    And treat those two imposters just the same;
    ...you'll be a Man, my son!" Rudyard Kipling

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