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  1. #1
    Sr. Apprentice
    Join Date
    Apr 2011
    San Antonio Texas

    Default Horsepower Increase

    How much horsepower would you gain by putting a GM Performance Parts Dual Exhaust System on a 2008 GMC Sierra with the 5.3L Engine???

  2. #2


    Probably around 5-15 hp depending on what other performance mods you have on your truck. You'll see much better performance gains when you combine a cat back exhaust with other mods such as a cold air intake, programmer, headers, cam etc.....
    04 ECSB Custom silver & grey, Soft 8's, BFG KO's, ReadyLift Leveling Kit, Hellwig front sway bar, K&N filter, DeeZee EZ-Down, Rhino liner, Alpine CDE103BT, Rockford 6.5's, 12" V.A.T. Hammer Pro in a Subthump box, Alpine PowerPack amp, Hifonics amp, BackRack w/ 55w 5000k HID KC Daylighters, KC light bar with 4 KC Slimlites, UWS toolbox, Shaved Antenna mod, Black Bowtie, LED backup, license plate, dome lights & 3rd brake light

  3. #3

    Join Date
    Jun 2006
    River Ridge Louisiana-4 miles W of New Orleans-didn't flood-water stopped 800 yards away.


    It is really really difficult to get actual seat of pants(which means low midrange rpm INCREASES IN TORQUE AND hp) improvements with todays really well developed OEM motors/exhaust/intakes.
    The OEM engineers know we want performance we can feel-and that means good throttle response and good torque hp in the 2000-3500 RPM range,
    HP improvements at the upper end- 4500 RPMS ON- we rarely ever "feel" except at a drag strips.
    And no way can you even feel 5-10 hp at the upper end.
    It is hard to tell performance improvement from noise when you are at 5000 RPMs with a V-8.

    The best bang for the $$ seat of pants improvements come from Nitrous Oxide kits.
    A "50 shot" will actually give you maybe 35 RWHP at 5000 RPMs- but it will also increase HP and Torque at 2500 RPMs.
    35 extra hp should be safe for a stock motor.
    Bigger shots- 75 hp and above are riskier for your motor.

    All the other bolt ons TELORVEHC will certainly add hp-maybe 50 at the crank 35-40 at the rear wheels- but all total they will be maybe another $800+ whatever the dual exhaust is-and the cam will almost certainly decrease low midrange torque/ HP
    There just isn't any free lunch with cams if you stay with stock displacement- to get high end power you give up some midrange low end power.
    Besides it is probably maybe 20 hours of DIY to do the cam/headers exhaust
    Maybe 2-3 hours max for the nitrous kit maybe $500?

    I'm always quick to put nitrous in others forlks vehicles- it can be hard on the motor/drivetrain-especially if you cut it loose at low RPMS.
    High end power adders are generally easier on drivetrains/motors if you don't push over the redline.

    It is also easier to remove a nitrous kit-and resell it-when you sell/trade in the truck.
    Folks generally assume a vehicle with headers/cams/dual exhaust HAS BEEN DOGGED-so they don't want to buy it.It frequently has been dogged of course-.Take the nitrous kit off before selling it and well no one knows(except if the seller is a young guy you can assume it has been dogged-I sure dogged mine when I was young)

    1998 suburban-
    1/2 ton

    199500 miles

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