Headers for 1999 L29 7.4l 4x4

Discussion in 'Exhaust' started by EllsworthBoofington, Mar 25, 2020.

  1. EllsworthBoofington

    EllsworthBoofington Newbie

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    Looking to upgrade my K3500. Seems there aren't many bolt on parts for this motor, but I'm interested in some new headers and exhaust.

    What do you recommend?
    What fits well?

    Thanks in advance!!

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  2. ZRoe

    ZRoe OBS Enthusiast

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    My plans are JBA long tube headers ceramic coated PN6822SJS for $620, the plain SS are $520. The instructions say they fit 4x4 trucks but I'm guessing it would be much tighter on a stock height truck than a lifter truck like mine.
    From the headers I'm going to do a custom dual side exit exhaust. My suburban fuel tank and the shackle flip I installed make it really tight to route even if I go straight out the back and I don't want to get fumagated while hooking up a trailer. Summit has a 3" aluminized kit PN671230 for $144 with hangers which is awful tempting even though I live in the rust belt of MI.

    I also picked up an 0411 pcm from a JY and am having black bear performance tune it. From my conversations with them, they understand the 0411 swap, but they usually use tow/haul mode as a sport shift mode NOT a towing mode which is my only disappointment. Otherwise the scan cable tune gets me going with a custom tune for about $375 not including the refundable deposit.

    All told those upgrades will cost me about $1000. I could go a little cheaper on plain steel headers but I don't want to be messing with them every couple of years. And honestly the JBA long tubes aren't any more money than the JBA or Gibson short tubes.

    If $1000 is too rich for your desire to upgrade then a better muffler and intake are the starting points and probably a mail order tune from Black Bear for ~$250 after that.

    My next $1000+ probably goes to an upgraded set of injectors from 5-0 Motorsports and a new cam/valvetrain/timing set.

    I've already got a down payment on the tune, but I'm open to hearing input if I should do injectors or cam before headers on this thing. I just figured if the injectors start to leak I can tell the wife I "need" the injectors but no one ever needs headers

    The cam I hope to catch before it grenades and "makes" me spend the money on a stroker kit to make it a 489!

    My thought with buying a k2500 was to eventually do a diesel swap either to a Duramax or a Cummins with a 6 speed manual. But honestly the big block motivates this thing pretty well and there is plenty of potential there without the hassle of the swap. Heck the only reason the diesels put down more power is the turbos and I've seen an article where a junkyard Vortec 7400 put down as much as the new diesels with just a cam swap, carb and turbo arrangement!


    Hope this helps, and looking forward to what others have to say.


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  3. Schurkey

    Schurkey I'm Awesome

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    Are you starting from OEM or from an aftermarket exhaust?

    Buddy of mine bought a '97 K2500 7.4L a long time ago. Used to pull a big travel trailer, and a boat behind that.

    He paid big money for Gale Banks headers, but went to a local muffler shop for replacement mufflers--he has two mufflers side-by-side instead of the single muffler with dual inlets and dual outlets.

    He's told me many times that the mufflers made more difference than the headers. The original muffler has big inlet and outlet connections, but is choked-down inside.

    If you buy "aluminized" exhaust parts, don't expect a long service life from them. The OEM stainless stuff lasts a long time, the aluminized pipes and mufflers much less.





    When it was me, I bought a Treasure Yard cat-back pipe, muffler, and tailpipe from another Extended-Cab truck, OEM stainless steel "single exhaust" from a '94 K1500 5.7L, and made it fit my '97 7.4L. The tailpipe and hanger brackets slid right into the existing hangers from the stock system. But I don't pull heavy trailers, I just push snow. No big-flowing exhaust needed.
     
  4. BNielsen

    BNielsen I'm Awesome

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    @Mangonesailor has Gibson headers and a full custom exhaust on his truck along with an 0411; and his truck rips! He did have some fitment issues on the flanges which resulted in some trimming but I don't think there was anything else. I think @Justin S has JBA shorties on his RCLB but he bought it with them already on there,

    My plan for my truck is JBA shorties and a full custom 3" exhaust with Magnaflow cats and glasspacks; I would love to find a set of Banks headers but that's like finding a needle in a hay stack at this point. I've already got the 0411 and my truck runs pretty good, there's acres of room for improvement in my opinion.

    JBA, Gibson, Hedman, and Hooker all make shorty and long tubes that fit Gen 6 454s, some don't have a provision for EGR but that can be remedied with a tune that deletes the EGR. A simple tune, and exhaust really wakes these big bastards up.
     
  5. Mangonesailor

    Mangonesailor I'm Awesome

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    Yeah, headers help a little off-the-shelf with a little extra HP and fuel milage bump.

    The big differences you can get out of a 454 without ripping apart the motor are LS1 28# injectors, headers, 0411, and a good tune. 3" out the headers to the muffler is good, but it needs to be necked down to 2.5" due to the HP you'll be making.

    Once you get PE mode activated, played with, AND have tow-haul mode... you'll think you've got a totally different truck.

    You're headed in the right direction, going with headers. It'll be worth having. It's been about 4-5yrs since I put my Gibson's on with he titanium ceramic coating. There's just a SMIDGE of surface rust, but you can't tell unless you really look close.

    Engine masters in motor trend has a good video of muffler comparisons for horsepower. I like a nice rumble and snap of glass packs, but I could probably grab some HP with the proper mufflers. Oh well.
     
  6. L29Sub

    L29Sub I'm Awesome

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    I used Gibson shorts on an L29 with good results. If doing it again, I'd lose the "dual" factory pipes and fab up a single 4" with big muffler. The collector fab is a fun project with engine in the truck. Gotta drop the torsion bars to pull factory collector...or cut it up.
    The Gibsons stayed tight and no leaks at the headers. They got a workout towing.
    Pic shows fabbed onto factory system.
    A 4" single will be tight, sound better and will allow double the hp that an L29 will make. A gmt400 diesel truck will make a good donor. A 4" diesel tailpipe extension will fit a Suburban without issues. [​IMG][​IMG]

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  7. rumpityZ28

    rumpityZ28 Newbie

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    I recently picked up a 2000 k3500 with the l29 and have been what kind of engine mods would help. Let me know how this exhaust mod works out
     

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