Thinking about new exhaust

Discussion in 'New Members Section' started by AMS3, Nov 7, 2019.

  1. AMS3

    AMS3 Well-Known Member

    Messages:
    1,060
    Likes Received:
    753
    Joined:
    Aug 8, 2019
    Location:
    Savannah Ga
    I'm thinking about replacing the stock manifolds with Kooks long tube headers and 3" stainless exhaust with no Cats or Resonators. Will this hinder the hp of my engine, or give it more hp?
     
  2. CaptnCrash

    CaptnCrash Full Access Member

    Messages:
    217
    Likes Received:
    38
    Joined:
    Jul 1, 2014
    You will get a boost. BUT it will take a tune and some post-cat O2 sensor simms or a tweak in the tune to eliminate them.
     
    AMS3 likes this.
  3. AMS3

    AMS3 Well-Known Member

    Messages:
    1,060
    Likes Received:
    753
    Joined:
    Aug 8, 2019
    Location:
    Savannah Ga
    Not sure what you mean by "post cat shims". What tuner do you recommend? I'll be having a Speed Shop do the work, as my knowledge of welding and tuning is about the size of a pea.
     
  4. CaptnCrash

    CaptnCrash Full Access Member

    Messages:
    217
    Likes Received:
    38
    Joined:
    Jul 1, 2014
    That would be post-cat O2 [ after the cats, downstream, etc ] sensor SIMMS [ no H ] ... If you remove the cats you either have to fool the PCM about the presence of the 2 post-cat or downstream O2 sensors and the results they provide about the condition of the cats, or get a tune that causes to PCM to not have a problem with them being missing.
     
    AMS3 likes this.
  5. rottenronnie

    rottenronnie Well-Known Member Supporting Member

    Messages:
    4,141
    Likes Received:
    2,058
    Joined:
    Jul 4, 2006
    Location:
    Calgary, Alberta
    I don't know if Kooks provide gaskets with their long-tubes, but I'd use the o.e.m. exhaust manifold gaskets for best results.

    Why do you want to run without cats anyway?
     
    AMS3 likes this.
  6. AMS3

    AMS3 Well-Known Member

    Messages:
    1,060
    Likes Received:
    753
    Joined:
    Aug 8, 2019
    Location:
    Savannah Ga
    I don't have to worry about DMV emissions testing where I live ( GA ) and want as much unrestricted flow as possible.
     
    TrailMix likes this.
  7. AMS3

    AMS3 Well-Known Member

    Messages:
    1,060
    Likes Received:
    753
    Joined:
    Aug 8, 2019
    Location:
    Savannah Ga
    Ahh yes, now I know what you're talking about. My last truck was an 05 QC Ram 1500 with the Hemi. I had Kooks headers and one of the O2 sensors was removed because I deleted the Cats. Engine light stayed on, but I didn't notice anything as far as loss of power, etc. The speed shop wanted $300 to make the light go out. I said no, I can live with it on.
     
  8. rottenronnie

    rottenronnie Well-Known Member Supporting Member

    Messages:
    4,141
    Likes Received:
    2,058
    Joined:
    Jul 4, 2006
    Location:
    Calgary, Alberta
    I'm just asking because these engines really stink without cats. I've known guys to put them back on because of it.

    I've got (4) decent high-flow cats on mine and I don't care about the small horsepower loss (if any). I shift it at over 6500 and there is no indication of restriction.

    Have fun.
     
    GSJake likes this.
  9. CaptnCrash

    CaptnCrash Full Access Member

    Messages:
    217
    Likes Received:
    38
    Joined:
    Jul 1, 2014
    I've been running without cats for 15 years now. I don't know "stink". Actually it's cats that smell like rotten eggs.

    At any rate, 4 cats = tons of heat, and really hot like melt stuff heat. They also = restriction and hp loss. I prefer to not set the woods on fire and get better mpg's.
     
    AMS3 likes this.
  10. rottenronnie

    rottenronnie Well-Known Member Supporting Member

    Messages:
    4,141
    Likes Received:
    2,058
    Joined:
    Jul 4, 2006
    Location:
    Calgary, Alberta
    Aughh.. If your cats smell like rotten eggs (after warmup) and are really hot, there is something quite wrong.

    As for power loss, with high-flows in your exhaust system, it's quite small.

    BIG difference between now and the early 1970s when cats failed, stunk like rotten eggs, operated at really high temperatures and were super-restrictive.

    Anyway, enjoy the headers, they should help.
     
    AMS3 likes this.
  11. GSJake

    GSJake Active Member

    Messages:
    207
    Likes Received:
    106
    Joined:
    Feb 13, 2018
    Dont do a straight exhaust, use some type of muffler. I have a Borla with the mufflers deleted (4 factory cats in place) on when I bought the truck a little over a year ago. Its loud which at first I liked.. then you drive it and it wears on you. I have an appointment on Tuesday for my exhaust guy to put a dual chamber "flowmaster" style muffler in place.
     
    AMS3 likes this.
  12. AMS3

    AMS3 Well-Known Member

    Messages:
    1,060
    Likes Received:
    753
    Joined:
    Aug 8, 2019
    Location:
    Savannah Ga
    Thanks for the advise guys, I'll take it under consideration.
     
  13. beastmode1

    beastmode1 Full Access Member

    Messages:
    580
    Likes Received:
    368
    Joined:
    Oct 2, 2014
    Location:
    Denver, CO
    Mine is stock less the last resonator at the back tail pipes. I removed it and it is pretty loud when you step on it. I get a lot of questions if i did anything to it.
     
    AMS3 likes this.