Remap My EFI After New Exhaust?


Do I remap my EFI after new Exhaust?

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Answer From Our Friends at DynoJet:

One big question is about re-mapping after changing the exhaust. Some say do it, other’s say it’s not necessary. More does than do not. Do I need to remap if I change aftermarket exhaust for another aftermarket exhaust? The work has been done.

Why do it again?

To get the most performance out of your bike remapping the fuel injection is a must. With just a setup of pipes installed, it is not imperative to remap the fuel curve as it will not run lean enough to cause any damage. If you were to purchase an exhaust that is similar in size, shape, volume, and design then remapping the fuel injection may not be necessary. But if you go from a set of slip-ons to a 2:1 full system remapping will be necessary.

Related Video:

EFI Buyers Guide and Exhaust Reviews and Installs

Have more questions? Check out the Tags below and our Harley Tips: A-Z index page to find some answers.

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47 Responses to “Remap My EFI After New Exhaust?”
  1. Nando

    Before you buy a intake or a new set of shiny exhaust get yourself a fuel management system as this is necessary for the proper function of your ride.
    I use a vance and hines fuelpak and its the best purchase I did for my bike and this avoids a dynotune every time I do a simple upgrade.

    • Drew

      My 2018 Street Glide will not start after installing Rinehart slip ons. What’s the problem?

  2. Don


  3. Michael

    What if I have a K&N high flow filter and change my stock pipes to a different style of stock pipes? I picked up a set that came off a newer touring model, but my 07 FLHT is in the fitment list. Part number is obsolete, but what I’ve found online shows they are a Screaming Eagle pipe yet they do not have anything on them saying Screaming Eagle. Service techs at local dealer say I am fine, bike is running awesome. I was told if there would need an issue it would be noticed right away. No back firing or choking out when I get on it. I still plan on having it dyno’d just to be safe

  4. Joe

    hey guys…I’m having a little problem starting my bike(2007 deuce)..It starts,but sometimes it takes afew time to fire..almost sounds like poor gas mixture…New battery and plugs..Any ideas??..thx loe

    • Customer Service Techs
      Customer Service Techs

      I don’t believe 2007 Deuce came carburated.
      Just because an m /c is lean, doesn’t typically mean that it should be hard starting.
      However, if the condition came about after you changed your exhaust or intake, you may want to look into it.
      Make sure you are using premium fuel.
      Try to think if the condition came on gradually or suddenly. That might help pinpoint when something changed and be a clue as to how to address the issue.
      Try checking for trouble codes.

  5. Daniel

    I have a 2005 flhtcui it has a cam k&n air cleaner and v&h slip-ons. Ihave the original head pipe If I go to a tru duel header do I have to remap? I do own the sceaming eagle software.

  6. Paul

    Hey I changed my pipes on my 2003 wide glide now I want to take the drag pipes and put a baffled set of Vance and Hines now do I need to feet carb or just rebuild it

  7. David

    I put a set of Vance and Hines Straightshot slipons on my 2016 Heritage should I remap mt EFI

  8. JR

    What about taking your bike to a stage one air cleaner set up? Should we map it?

  9. Richard Runyon
    Richard Runyon

    I’m going from bassani 2n2 street sweepers to Vance and Hines 2n1 big radius, bike was mapped 2 months ago when bigger cams were installed will I need to remap it

  10. Russell johnson
    Russell johnson

    I have a 14 ultra limited, slip-on only, I decatted a stock head pipes from a 15 road glide, would I need to remap if installed

  11. stan

    I have a Harley 2016 fld switchback and want to go from stock exhaust to vance and hines slip-on exhaust do I need to remap with just slip-on exhaust? ps. the bike has stage 1 already

  12. Glenn

    I’m confused basically because options are so vast on exaust. I own a 2016 dyna switchback. I love my bike, so smooth compared to all my sportsters over the years. But, stock pipes are not safe enough for me. My sporty when I came around a corner , the car in driveway ready to pull out heard me coming. I don’t need more response, or power, just the sound I’m used to. I like V&H pipes, but am fine with slip on. If I pick a Vance and Hines slip on,do not change air intake, do I need the fuel upgrade or not. ? It really should be a yes or no, not a well maybe.. lol

    • White Horse
      White Horse

      it absolutely can be a maybe, but more like a probably. all HD come from the factory running lean, put on a slip on is going to make that slightly worse… it’s not going to run the way it should so yeah I would get a fuelpak and remap. I did a V&H slip on with my heritage and it ran horrid until I remapped and now it runs great. you also should probably get either a high flow air filter or full air cleaner kit to better help the lean issue after the pipe install.

  13. Don Eitel
    Don Eitel

    I just put Rinehart racing 4″ true duals and a new air cleaner kit on my 2010 Streetglide it already has a Powercommander on the bike, my question is do it need to be remapped again? The bike had a aftermarket 2into1 system previously. Thanks

  14. Don Figuerres
    Don Figuerres

    Have a V&H Fuelpak on ’07 Street Bob – 96 ci – tuned for V&H Big Radius 2-2. Just replaced pipes with Stepped drag pipes 2-2, no baffles or torque cones. Do I need a re-map and if so where can I find it as I don’t think V&H carries this aftermarket manufacturer (Ambush – AccessoriesHD)…Thx!

    • Customer Service
      Customer Service

      Hi Don. Vance and Hines has excellent customer support. Whenever we do not see an accurate map description for a bike we are tuning, we just call them up.
      9 out of 10 times they will have a listing for your performance combination and refer you to the most compatible map.


  15. andre

    i have a 2017 street glide special I first brought 4.5 in slip on and at that time I installed the pro street tuner, then I purchased a slimline dual header system with a stage 1 screaming eagle air cleaner , do I need to dyno the bike at this time or will the screaming eagle street tuner do the job

    • Customer Service
      Customer Service

      It is not typically nesscary to need a Dynomometer to achieve a smooth tune for the street. It is, however, the best way to tune if your budget allows.
      If the bike runs fine with the new headers, you can leave be.
      If you experience decel pop or any “flat spots”, you will have to alter your current tune. It is ok to give it a try 1st.

  16. Mark

    Why would I need to remap or buy a tuner for intake and exhaust upgrades? Isn’t that what the O2 sensors are for? continuously monitoring the exhaust and making AFR adjustments as needed?

    • Customer Service
      Customer Service

      The stock ECM on your Harley Davidson has a specific “window” in which it can adjust the fuel mixture to accommodate for changes. Changes in temperature, altitude and air pressure are easily within this window. An exhaust change without intake is borderline.
      The ECM may be able to compensate, but you will inevitably be making a lean situation, worse.
      Changing intake with pipes puts you completely outside the window. The system will not have the ability to introduce enough fuel to compensate for the additional air flow.
      We suggest Power Commander, Power Vision, or Vance and Hines FP3. Anything else on the market may be cheaper but pale in comparison.

  17. Don Galyardt
    Don Galyardt

    I have a S&S 2 into one exhaust in which the EFI was mapped with Race Tuner. Just installed a D&D 2 into 1 pipe on bike. very close on length. had high air cleaner on for fist mapping also. Do you think I should have it dyno tuned again?

    • Customer Service
      Customer Service

      Hello Don,

      We would not suggest another Dyno session unless you were to change tuners, or if performance is adversely affected.

      Mark FMH Video Membership

      We’d love to have you be a part of our community. We are convinced you will enjoy the benefits of becoming a member and having access to the best instructional how to videos and professional tips. We would like to offer you a special promotion for your first year membership.

  18. Donna Veal
    Donna Veal

    I want to put Vance & Hines short shots on my 2010 Soft Tail Deluxe. Where can I get a remapping disc for that?

  19. Earl

    I have a 2011 street glide and I will be installing rinehart true dauls and an air cleaner. I also baught a Vance and Hines throttle pack. Do I still need to remap my bike after all is installed

  20. Joseph

    I just put Samson 36” on my 2014 softail is it safe to run with out a remap

  21. Doug

    I have a 16 Roadster with V&H Straight shots w/ no baffle. Do I need to remap the fuel system or tune my bike? I noticed at 2500 RPM’s the bike was cutting out a little. Didn’t do it the day before on a 70mi ride but did on a 3mi ride. Thoughts?

  22. wade

    Changed exhaust on a true dual header set up from 4″ to Bassini fishtail with baffles. Re map necessary? Seems to run about the same. Any improvement to the map necessary to compensate for the change in diameter of exhaust? Thanks in Advance

  23. Don

    If I went from stock into a 2:1 full system can I ride for a couple days without causing damage. My tuner delivery was delayed.

  24. Mark

    Just got a 2017 soft tail slim s. My first bike. I want to get the hacker custom exhaust mayhem. It come w a fuel map for 250 xtra. Will that also take care of a new k&n air filter/ intake , or should I ask hacker if it will be programmable for further updates later ie: k&n or other air intake system ???

  25. Truck

    I took the poor mans way and gutted my stock slip on muffler. Didn’t change intake or pipes and it is all stock. Do I need to remap my injection?? It is a 2010 roadglide.

  26. Leon

    I’m going to purchase vance & hines downsweep pipes for my 2018 Harley Lowrider.What type of air filter shoud I upgrade to ?

  27. Lee greenberg
    Lee greenberg

    If u have 2012 softail slim and want to remove factory slip ones, can u then baffle the straight factory pipe that is left on the bike ? And which baffles would work best? Thank asking for the sake of knowledge had a friend ask me and hell I wanna know to!!

  28. Jim Riter
    Jim Riter

    I have a 2014 softail slim i put a short set of LA custom drags on bike we after 2 years it screwed up my front valve and both pistons i had motor rebuilt, my question is if i use AR cones do i need baffles or should i just change to another exhaust

    • Customer Service
      Customer Service

      Hi Jim. If the m/c is tuned correctly, it is unlikely to experience engine damage. You should run whichever system you like. With or without baffles. Those cones are useless.
      If you are uncertain about the correct tuning, call the tuner manufacturer directly. Not sure what you are running but Power Commander and Vance and Hines have excellent customer service.
      Mark-Fix My Hog

  29. ronald bieber
    ronald bieber

    I have a 2013 harley ultra classic with a 103 eng. I want to remove my stock exhaust and install a complete 4 inch reinhart exhaust from the motor back is it necessary to do a efi mapping?