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  1. #1

    Default 350 open header truth from rumors

    so i have a 89 Chevy with a 350 in, i would like to run open headers in it. first id like to know.... Ive searched else where that lose or back pressure=bad and others saying no back pressure is good. also will it get me better gas mileage? anything else i need to know before doing this? thanks

  2. #2


    Open headers will make your truck have lag which is loss of back pressure. The back pressure can be good and bad in both ways too much back pressure can rob you of hp and torque and too less back pressure will generally do the same thing. It also depends on what all you have done to your truck and everything also.

    2008 Chevy Silverado Ext. Cab Lt Z71 5.3 V8
    7.5 Inch Rough Country Suspension Lift
    RBP Replica Grille Black w Chrome Rivets
    Recon Smoked Cab Roof Lights
    N-Fab Powdercoated Gloss black Cab Length Nerf Steps
    5% Tint over 20% all the way around / 5% Eyebrow Strip
    AVS Smoked Window Visors
    Z71 Stickers Black & Metallic Silver
    Tow Mirrors / Smoked Turn Signals
    XM Satellite Radio Fin / Color Matched
    Interior Plastic Pieces / Color Matched
    Power Acoustic Tweeters
    Painted Bowties / Color Matched
    Painted Door Handles / Color Matched
    Smittybilt Bull Bar / Color Matched
    Custom Rolled Edge Exhaust Tips / Color Matched
    Custom 2.5 Inch Cat Back True Dual Exhaust
    Flowmaster Super 40 Series Dual in / Dual out
    Magnaflow Tru-X Pipe
    K&N Air Filter
    18x9 Rockstars Machined Black
    Center Caps / Color Matched
    33.13.50 Nitto Terra Grapplers
    New Front Wheel Well Liners
    Eagle Eye Black L.E.D. Tailights
    Eagle Eye Black L.E.D. Third Brake Light / Smoked
    Eagle Eye Black L.E.D. Halo Projector Headlights
    Notto HID Kit 10,000k Low beams
    Recon L.E.D. Light Bar
    Buschwacker OE Style Tailgate Cap
    AMI Gloss Black Antenna
    Debadged Chrome Lettering
    Door Molding Removed

  3. #3
    Sr. Engineer
    Join Date
    May 2009
    Manitowoc, WI


    In a perfect world.. yes, less backpressure would give you more power. However, your truck assuming its stock has the swirl port heads which aren't very good for performance to begin with, so you're not going to gain much by switching from the stock manifolds to headers, and the gains going from headers connected to an exhaust system vs. open headers are going to be even less if any at all. If you had a high compression motor with some fancy high flowing AFR heads and a big cam, you'd see some gains. A stock late 80's TBI engine, not so much.

    The only thing you can guarantee with open headers is you'll have pissed off neighbors, occasional stops by the local law enforcement, and ringing ears after every 10 minute drive.

  4. #4


    Yeah i totally agree man! My buddy has a 80 something model F 150 single cab short wheel base with 302 bored with open headers and exhaust cut under the cab and his truck was slow as hell and had allot of lag but was too damn loud to be driving on the road lol!

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