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3" exhaust too much for a 305? (Updated)

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Bross82, Sep 23, 2003.

  1. Bross82

    Bross82 1/2 ton status

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    3\" exhaust too much for a 305? (Updated)

    Hey, I have full 2" dual exhaust system on my 85 K5 Blazer. I'm going to replace this exhaust system soon. The driver side pipe broke after the muffler and the passenger side cat is falling apart on the inside.

    I eventually want to put a 454 in, but this probably wont happen for atleast a few years. Basically, any part I replace I try and upgrade and modify with that in mind. This is why I'm considering a 3" system. Is a 3" exhaust too much for a 305 with 140,000 miles on it? will there be enough back pressure? Does a 3" really give that much more power, or would I be better of with a 2 1/2" system?

    also, what does anyone think of these mufflers?
    dynomax ultra flo muffler

    Thanks,
    matt
     
  2. shane74

    shane74 1/2 ton status

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    Re: 3\" exhaust too much for a 305?

    2 1/2" is plenty even for a 454. I wouldn't go above that with a 305. They don't have much low end torque as it is. Another question is..are you running headers or stock manifolds? I run 2 1/5" duals on my 350, but I left the stock manifolds on for a variety of reasons. 1) To keep some bottom end torque, and 2) They stay sealed up better than most headers.

    Those two reasons are very debatable depending who you talk to and what day of the week it is /forums/images/graemlins/grin.gif, but that is what works for me. Do the research and do what works for you.
     
  3. jekbrown

    jekbrown I am CK5 Premium Member GMOTM Winner Author

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    Re: 3\" exhaust too much for a 305?

    me thinks stock manifolds prolly do stay sealed up better, unless you have some really high end headers with good thick flanges.

    j
     
  4. Bross82

    Bross82 1/2 ton status

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    Re: 3\" exhaust too much for a 305?

    i'm running stock manifolds.

    does anyone have an opinion on the above listed mufflers? i would like something similar to what i have now...some turbo mufflers that are supposedly part of a flowmaster system the guy i bought the truck off had installed. they arent much bigger than the pipes, are rectangular in shape, and have indents on each rounded edge around the muffler about every 1"-2"s. i have checked flowmasters site, and they dont seem to currently carry this anymore. the closest i found was the dynomax mufflers i linked to above. i want as much performance as possible, but dont want to compromise the way it sounds either.


    thanks
     
  5. shane74

    shane74 1/2 ton status

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    Re: 3\" exhaust too much for a 305?

    Well...opinions are like @ssholes.... That being said, you asked for it! /forums/images/graemlins/eek.gif

    I was going to run Flowmasters as well, then I talked to a buddy of mine that runs an exhaust shop. I ended up going with good sized turbo mufflers instead. If you do a lot of freeway driving and want quiet, those may be a bit too noisy for you. IMO flowmasters are great, but they aren't always what you need. Also, my turbos sound great and cost $50 each. They work for me. I know there are a few on the site who have heard my rig and can attest to the sound of it. When I get on it, you KNOW it! /forums/images/graemlins/thumb.gif /forums/images/graemlins/cool.gif
     
  6. jekbrown

    jekbrown I am CK5 Premium Member GMOTM Winner Author

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    Re: 3\" exhaust too much for a 305?

    yeppers, shanes rig sounds cool. /forums/images/graemlins/grin.gif I have a flowmasta fitty, and I like it too. dunno on the d-max, never had or heard one,

    j
     
  7. Can Can

    Can Can Pusher Man Staff Member Super Moderator

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    Re: 3\" exhaust too much for a 305?

    Dynomax Super Turbos are one of the best flowing turbo mufflers on the market. They are pretty subtle at idle, but tromp on the gas and they'll turn a lot of heads.

    FWIW, I have a 2 1/4" dual exhaust setup using the stock manifold and I run the Super Turbos. I have a 305 as well. I'm happy with the combination.
     
  8. sdavid

    sdavid 1/2 ton status

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    Re: 3\" exhaust too much for a 305?

    Check out www.flopro.com and see if any of your local shops carry them. They have a flowmaster knock off (V-Force) that is almost exactly like a 2 chamber flowmaster (40 series, the original one and the loud one). Should be less expensive. Flowmaster will have a raspy and aggressive sound due to no fiberglass packing, turbos will be more mellow w/ a deep blop, blop sound. I like flowmasters and the way they sound, but that's my opinion.
     
  9. rjfguitar

    rjfguitar 3/4 ton status GMOTM Winner

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    Re: 3\" exhaust too much for a 305?

    I have dual 2.5 inch pipe, dual 40 series flowmasters,dual 5" tips, and no converter of course. /forums/images/graemlins/thumb.gif I kept the stock manifolds because of sealing and smog issues. but with my cammed up 406, when I get on it it sounds VERY AGRESSIVE and with the 5" tips it also stays pretty deep toned. It sounds like a WAY pumped up muscle car with flowmasters at 5,200RPM's. As far as noise at freeway speeds between my boggers and exhaust I can't hear anything else. /forums/images/graemlins/thumb.gif
     
  10. jekbrown

    jekbrown I am CK5 Premium Member GMOTM Winner Author

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    Re: 3\" exhaust too much for a 305?

    [ QUOTE ]
    ...dual 5" tips....

    [/ QUOTE ]

    thats bling bling! /forums/images/graemlins/grin.gif

    j
     
  11. rjfguitar

    rjfguitar 3/4 ton status GMOTM Winner

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    Re: 3\" exhaust too much for a 305?

    [ QUOTE ]
    [ QUOTE ]
    ...dual 5" tips....

    [/ QUOTE ]

    thats bling bling! /forums/images/graemlins/grin.gif



    [/ QUOTE ] Uh, bling whatever, They make a big difference in tone. Makes it deeper and meaner sounding. /forums/images/graemlins/deal.gif And it makes everyone say " oh, Sh!t , those look bad ass!" When they see them /forums/images/graemlins/thumb.gif
     
  12. 55Willy

    55Willy 3/4 ton status

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    Re: 3\" exhaust too much for a 305?

    On my 79 jimmy I had dual 2.5 flowmasters and 3" tips. the tips do make a difference. my buddy had a 86 with the same pipe and mufflers but used straight "pencil" tips, sounds way different. both were running headers.

    On my wagon with a 305. I'm running a crossover pipe and a single 3". not sure yet if I'm gonna do a dual outlet muffler or keep it single. my reasons are:
    1) need the room for the anti wrap bar
    2) fuel injection lines and filter are next to the t-case where the normal passenger side pipe would go.
    3) one muffler is cheaper then two.
    4) it's just a 305

    but my 427-440 (not sure yet on bore and stroke combo) that is going into my 40 chevy coupe will get dual 3" with 3 chamber flows and big tips.
     
  13. jekbrown

    jekbrown I am CK5 Premium Member GMOTM Winner Author

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    Re: 3\" exhaust too much for a 305?

    lol, when i see the coffee can tips i just point and laugh... maybe Im the only one. ur rig, so its all good. /forums/images/graemlins/grin.gif /forums/images/graemlins/thumb.gif /forums/images/graemlins/rotfl.gif

    j
     
  14. loudnowlouder

    loudnowlouder 1/2 ton status

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    Re: 3\" exhaust too much for a 305?

    the dymomax mufflers are great in my opinion, cheap, sound great, and they're quiet at idle. as already pointed out if you mash on the throttle they really open, i second that statement. i got the full kit from jegs for my truck, all bolt on, all dynomax, pretty cheap all in all, the fit wasnt perfect, but couldnt be beat for the price since i didnt have the truck running at the time to take it to an exhaust shop. definately wouldnt recommend 3 inch pipes, just not necessary and it'll hurt performance on your 305.
     
  15. Bross82

    Bross82 1/2 ton status

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    Re: 3\" exhaust too much for a 305?

    cool, thanks.

    another thing. what do you recommend more for where the pipes come out. should they just come straight out the back, this is how its set up now, or turn behind each rear tire?? I'm thinking more in terms of trying not to get either pipe crushed while four-wheelin

    thanks
     
  16. loudnowlouder

    loudnowlouder 1/2 ton status

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    Re: 3\" exhaust too much for a 305?

    if you ever use your back window, dont put them straight out the rear, anytime that window is down, it'll suck the fumes right into the cab
     
  17. rjfguitar

    rjfguitar 3/4 ton status GMOTM Winner

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    Re: 3\" exhaust too much for a 305?

    My tips dump right between the rear axle and the fuel tank in a V shaped spread. If I could figure out how to get the picture from my member's rides folder to my post I would put it on here. /forums/images/graemlins/confused.gif
     
  18. jekbrown

    jekbrown I am CK5 Premium Member GMOTM Winner Author

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    Re: 3\" exhaust too much for a 305?

    dump it down and towards the side right after the muffler. less to get caught on rocks.

    j
     
  19. doctor4x4

    doctor4x4 1/2 ton status

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    Re: 3\" exhaust too much for a 305?

    400 sbc and dynomax turbo.s love em and so do all that here em except the cops :- ) got pulled over cause it ( "sounded like you were going to fast threw that light slow it down a little by the way what ya got under the hood ")
    true story
    /forums/images/graemlins/thumb.gif
     
  20. blazinzuk

    blazinzuk Buzzbox voodoo Premium Member GMOTM Winner

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    Re: 3\" exhaust too much for a 305?

    Daul 3" would be fine. If you are running 9000rpm on the high banks of daytona. if you are going to put a 454 in later I would put daul2.5 on it right now then you will be good to go. Someone also said they run exhuast manifolds to increase tourque headers will increase tourque across the board an engine can be likened to an air pump the better it gets air in and out the better it runs /forums/images/graemlins/rotfl.gif /forums/images/graemlins/rotfl.gif
     

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