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Exhaust choice - do I need true duals or a 3" single system?

Discussion in 'The Garage' started by BurbinOR, Apr 5, 2003.

  1. BurbinOR

    BurbinOR 3/4 ton status

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    Exhaust choice - do I need true duals or a 3\" single system?

    Here's the setup - my 3/4 ton Burb has the current ALL original exhaust on it, including the factory cat (yikes), which is a two into one right before the transfer case setup (y-pipe from passenger side over to drivers side), and 2.25" out the back. My choices are to replace what is there with basically the same setup but with it being 3" from where the Y comes together out the back with a new high flow cat and Magnaflow muffler...........OR true duals 2.5" down each side. Difference is about $300 between the two - for what benefit is the issue.

    With my 350TBI will I really see any improvement with going to true duals? It is not a revver/toy type motor like my TPI406 equipped K5 was, it is a camping/hunting/light wheeling rig. If it ever revs over 4500 I'd be surprised.

    Opinions, CK5 brothers and sisters, por favor.......... /forums/images/graemlins/1zhelp.gif
     
  2. Z3PR

    Z3PR Banned

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    Re: Exhaust choice - do I need true duals or a 3\" single system?

    I see lots of people being very happy with a 3" single exhaust system. Do you plan on headers ?? Any mods to the engine ???
     
  3. Hossbaby50

    Hossbaby50 3/4 ton status

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    Re: Exhaust choice - do I need true duals or a 3\" single system?

    Either way works, and lots of people will fight about which is better. I personally have 2 1/4" duals with high flow cats. 3" is just fine though too. Personally if you don't want or need dual for the look or whatever reason 3" is the way to go. I wanted true duals (so what it is illegal) so I got it. I wanted the sound, the look, and the flow. 3" would have worked fine, and possibly helped out with a little more low end torque then the duals. Oh well, to each there own. If you don't really want it and don't want to spend the extra cash on it then just get the high flow 3" setup.
     
  4. Chris_T

    Chris_T 1/2 ton status

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    Re: Exhaust choice - do I need true duals or a 3\" single system?

    I have no Cat ('72), but I went from 2 1/4" true duals to a single 3" and like it much better. I think it's a personal preference thing. I did notice a bit better "seat of the pants" feel to the new exhaust system, but the old one was nothing to brag about, so a good dual system may have given me the same feeling or more. I guess my point is I have no complaints with a single 3"
     
  5. jms

    jms 1/2 ton status Author

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    Re: Exhaust choice - do I need true duals or a 3\" single system?

    350 w/ vortec heads, Q-Jet, and TES headers here. I had single 3" all the way from the Y-pipe back (including cat), and didn't like it very much. Went back to single 2.5" (including cat), and seat of the pants sez low end response is better, and it's not as loud (I'm too old for exhaust noise). As for restrictions in the exhaust, in my case the stock '85 cat was the culprit. The high flow cat (sorry, no part number, the midas guys put it in, looks like the stuff Summit sells) made all the difference, no matter whether 3" or 2.5". The reduction in engine braking when I coast is really noticeable. Just my $0.02, michael
     
  6. Catman

    Catman Registered Member

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    Re: Exhaust choice - do I need true duals or a 3\" single system?

    I'm running a Flowmaster 3" cat back system from Summit and it woke the old 350 right up. /forums/images/graemlins/thumb.gif I've heard that if you run duals with the rear window down you suck exhaust into the cab. CO2 is not good for you.
    /forums/images/graemlins/k5.gif /forums/images/graemlins/usaflag.gif /forums/images/graemlins/usaflag.gif /forums/images/graemlins/usaflag.gif
     
  7. k20

    k20 3/4 ton status

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    Re: Exhaust choice - do I need true duals or a 3\" single system?

    well its not the duals that sucks it in, its more the exit location from how i understand it.
     
  8. HarryH3

    HarryH3 1 ton status Author

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    Re: Exhaust choice - do I need true duals or a 3\" single system?

    The area of a 3-inch pipe is 7.0686 square inches, while the area of a 2-inch pipe is 3.1416 square inches. So a single 3-inch pipe can flow more than dual 2-inch pipes (6.2832 square inches combined) . /forums/images/graemlins/eek.gif

    A 2.5-inch pipe has an area of 4.9087 square inches, so dual 2.5's would net you 9.8174 square inches.

    After a discussion with the folks at Borla several years ago, they assured me that 2-inch duals would be plenty of exhaust for a stock '87 'vette 350. So a single 3-inch should suffice nicely, save you some cash, and leave room under your truck for other stuff. /forums/images/graemlins/wink.gif And if your state ever implements stricter emission controls, then you won't have to swap things back to single exhaust again later. /forums/images/graemlins/cool.gif
     
  9. jekbrown

    jekbrown I am CK5 Premium Member GMOTM Winner Author

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    Re: Exhaust choice - do I need true duals or a 3\" single system?

    benefits of true duals: engine can breathe better, easier the route past front driveshaft since you dont need a y-pipe.

    negatives of true duals: if your rig is new enuff to require emmissions inspections you need 2 cats in addition to 2 muffs... $pendy.

    personally I run single exhuast on my mild 350. Edelbrock headers run into a single 3" system... high flow cat, flowmaster 50 and out. works for me.

    j
     
  10. thatK30guy

    thatK30guy 1 ton status Premium Member

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    Re: Exhaust choice - do I need true duals or a 3\" single system?

    I prefer the single 3" for backpressure reasons. Would make for a more equal pressurized flow since you will have the necessary backpressure built in as they flow since when you run true-duals, they act like "blow-bys". Thats the reason you see those "H" pipes where you fit them between the two dual pipes to equalized the backpressure. Running a single will eliminate that problem and be much cheaper, too.

    BTW, I wouldn't run headers if I were you. Just leave the factory manifolds alone. But if you want to improve the air flow on the manifolds part, get some aftermarket types like the Edelbrocks. Go to their website and read about them. /forums/images/graemlins/cool.gif /forums/images/graemlins/thumb.gif
     
  11. midget

    midget Registered Member

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    Re: Exhaust choice - do I need true duals or a 3\" single system?

    One of the main troubles I have had with the single 3" is the stupid pipe that snakes under the front driveshaft. I havn't seen anyone rout a different way and it is just looking to hit something hanging down like that...that is the main reason i think i will go back to duel 2.5 "
    I agree, dont do headers,, major pain in the 4ss unless you spend big bucks then i hear they do pretty good.. i guess 200$ wasn't enough for the ones i got. i have had some really bad luck with headers..
     

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