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2 1/2 or 3 inch?

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by reddog64, Feb 10, 2002.

  1. reddog64

    reddog64 1/2 ton status

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    ok... 1978... so no cats... 454/th400 I had 2 1/2 on the blazer with 50 series flowmasters and liked it but it was only a 350... so with a 454 should I do 3 inch?
     
  2. BlueKnight

    BlueKnight 1/2 ton status

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    its all a matter of back pressure. I your engine wants to breath 2 1/2 to 3" would be agood choice. mine is 2 /12 to the front of the Flows and 3" out a bit of both. HAS a deep powerful bass with no rapping sound.

    <font color=purple>79' K-5 396cid 600hp, TH350, NP203</font color=purple>
    <a target="_blank" href=http://blueknight.alloffroad.com>http://blueknight.alloffroad.com</a>
     
  3. reddog64

    reddog64 1/2 ton status

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    does anyone have 3 inch with a 454?
     
  4. TXsizeK5

    TXsizeK5 1/2 ton status

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    If you are running true duals, i hear 3" doesn't have enuf back pressure. I duno if that holds true with the 454. But If you are going true dual id go 2 1/2 or so... if you are running the y-pipe or whatever, go for 3"

    87 Custom Deluxe
    305/Sm465/ NP208
    4.56 , 35" BFG Muds, CatCo Cat & Series 40 delta flow 3" tips.
    6"Springs, Tranny, & Engine coming soon.
     
  5. Lonnie

    Lonnie 1/2 ton status

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    I run dual 3" on a built 427 with good torque. If a stock 454 you may be better off with dual 2-1/2" to retain low end torque, especially if you do not have long tube headers. 3" is not necessary until over 450hp. With properly sized headers, exhuast size has little effect on low end torque. With shorty headers or manifolds, exhaust size can greatly affect torque. 3" will be noticibly louder with the same type muffler. Smaller tail pipe diameters (eg. 2-1/2" tails with 3" before mufflers) can help lessen noise with minimal power losses. This is due to the loss of heat/energy after the mufflers. Hope this helps.
    Lonnie
     

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