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Exhaust Suggestions?

Discussion in 'The Garage' started by JAKDUPBLUK5, May 20, 2003.

  1. JAKDUPBLUK5

    JAKDUPBLUK5 Registered Member

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    Hi everyone. I have a '87 k5 with the 5.7 and throttle body. I recently put on the holley 670cfm throttle body and its topped with a 4 inch tall K&N. I also removed the A.I.R. system a long time ago, and the engine has an aftermarket .450 lift roller cam in it. I have the flowmaster 1 into 2 exhaust on it now but with the holley its not enough flow and i always wanted headers. So I just bought some 1 1/2" primary 3" collector headers. I am going to just buy a exhaust tubing kit to go all the way bnack and I am going to add on a balance tube and use some dynomax terminator mufflers.
    My question is, should i go with 2 1/4" pipes or 2 1/2"? I want all the power i can get but i dont want it to be too loud either. It's already loud with still having the manifolds and my dad will prolly give me crap about it if its too much louder. Will 2 1/4" be enough to give me more power than i have now and improved fuel economy (by the way its also got AOD). You guys are the experts and I'd really appreciate it if you could give me your opinions.

    thanks /forums/images/graemlins/k5.gif
     
  2. mudhog

    mudhog THEGAME Staff Member Super Moderator

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    i would run the 2 1/2 in-fact i do lol
     
  3. JAKDUPBLUK5

    JAKDUPBLUK5 Registered Member

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    and how does the 2 1/2" perform and sound on yours? and what engine/mods are you running?
     
  4. mudhog

    mudhog THEGAME Staff Member Super Moderator

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    sounds and works awesome /forums/images/graemlins/thumb.gif i am running a basically stock 350 with a 4x4 cam edelbrock intake and carb
     
  5. JAKDUPBLUK5

    JAKDUPBLUK5 Registered Member

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  6. JAKDUPBLUK5

    JAKDUPBLUK5 Registered Member

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    Anyone else have an opinion on my lil predicament?
     
  7. MousePowrd

    MousePowrd 1/2 ton status

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    I have 2 1/4 in and dynomax mufflers. Nice and quiet at idle, and its really throaty when you are on the gas. Engine is stock except for headers and K/N
     
  8. JAKDUPBLUK5

    JAKDUPBLUK5 Registered Member

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    Come on guys i really need your input. I'm not too good at trusting my own decisions and im also going to be spending what seems like a lot of money to a poor college studetn like me and i want to get what is going to be right for me so.....? /forums/images/graemlins/k5.gif
     
  9. yellowK20

    yellowK20 Well Lubricated Premium Member GMOTM Winner

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    2-1/2" pipes That's what I like to run on a small block sounds good and flows good Shaggy thinks I'm nuts /forums/images/graemlins/crazy.giffor runnin' that big a pipe but it works for me and sounds good /forums/images/graemlins/thumb.gif
     
  10. Brian 89KBlazer

    Brian 89KBlazer 1/2 ton status

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    I'll say the same as the others......dual 2.5". I have dual flowmaster 50's and called them up to see what size I should run with a reasonably modified 350. They told me that if I planned more than a stock rebuild on a 350, 2.25" would start getting restrictive to HP but the dual 2.5" would not be too big as to hurt low end torque
     
  11. Blue85

    Blue85 Troll Premium Member

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    Some numbers for you to think about:
    single 3" pipe: 7.1 in^2
    dual 2.25" pipe: 8.0 in^2
    dual 2.5" pipe: 9.8 in^2

    With big headers and dual 2.5" pipe, you really don't have much backpressure
     
  12. JAKDUPBLUK5

    JAKDUPBLUK5 Registered Member

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  13. sdavid

    sdavid 1/2 ton status

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    I think with headers and high flow mufflers, I would go with 2.25" pipes to help with low end torque. But it would probably be so close that you might not be able to tell a difference. 2.5" pipe will be a deeper tone, but I don't think it would be any louder. Basically, get the size you like b/c it's your $ and you do not want to have to do it twice.
     
  14. JAKDUPBLUK5

    JAKDUPBLUK5 Registered Member

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