2021+ BMW S1000R Stage 2 w/ IAT Relocation Kit and Intake Flapper Kit



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Product Description




Following the release of our popular Stage 1 Flash we needed to sit down and really start to look at what the 2021 truly has to offer.  Anyone with our Stage 1 Flash will tell you how much it improved acceleration, fixed the OEM idle issues, and made the motorcycle feel better and more smooth overall.  Stage 2 has months of research and development behind it as well as datalogging and dyno testing.  The new 2021 S1000R is familiar to us but also completely changed.  To that end we were able define new ECU strategies that we can help make this already impressive bike even more impressive.   Stage 2 is a feature map making the bike more consistent, more reliable, and smoother.  Combined with our IAT Relocation and intake flapper delete kit results in a much improved motorcycle!


Includes all benefits of Stage 1, with these added features:

  • Octane adjustments
  • Corrected cold/warm start idle
  • Re-calibrated timing
  • Lower max lambda, leaner high RPM Target
  • Higher RPM limit without throttle cut for roll racers
  • 30% faster up and downshifts
  • Includes our IAT extension kit and intake flapper removal kit


Octane adjustments for auto adaptation on pump gas for US and international fuels 91-94 octane 95-100 RON. Utilizing the multiple ignition maps and factory widebands, we are able to increase performance based on knock detection. This also means if you have some bad fuel, the motorcycle will still compensate and put the bike into safety mapping just like the OEM ECU would. This ensures your bike stays consistent and reliable.

Corrected cold/warm start idle for finer tuning beyond Stage 1. Stage 1 did a lot to correct the startup issues the 2021 S1000R was having. Stage 2 goes a step further. There is no longer a high idle that transitions into a lower idle. The idle remains static without any lean popping, idle hunting or stalling.

Re-calibrated timing for higher octanes to make use of race fuels on same tune. The 2021 S1000R has multiple ignition maps and based on knock feedback, the bike will start to adjust to different timing maps. This means if you have a high octane fuel in the bike or race fuel and knock isn’t present, the bike will transition to a more aggressive timing map automatically. A more aggressive timing map will safely allow the bike to make more power. No more flashing every time you want to use race gas although we can still provide specific race fuel mapping designed to be used on ONLY race gas. This feature is most beneficial when you are on the track or street and don’t have your handheld available to swap maps.

Lower max lambda, leaner high RPM Target for a few more horsepower. AFR (air/fuel ratio) adjustments have been made to Stage 2 to be more aggressive to get a little more power out of the bike while remaining safe.

Higher RPM limit without throttle cut for roll racers (optional) With Stage 2 we are able to raise the RPM limiter to 12,500 RPM while also making sure the raised RPM event is not stored in the ECU. We have also adjusted the spark and fuel cuts so when the rev limit is hit, the bike doesn’t feel like you slammed on the brakes, it’s more gentle now.

30% faster up and downshifts over Stage 1 and now allows the use of fast shift sensor products on the market if desired.


As many of our customers know, our IAT (Intake Air Temperature) Kit for the 10-19 BMW S1000RR has been extremely popular and shows noticeable gains on the street and even dyno.  This IAT strategy was first used by Dinan (BMW) in the 1990’s.  However, the 2021 S1000R included some serious changes and required a new strategy for this project.

New for 2020 is our Intake Flapper Removal Kit.  The 2021 S1000R now has flappers in the intake tract, these flappers only allow a small amount of air to pass through to the engine until 6000 RPM when the flappers finally open.  When the flaps aren’t open it allows for stagnant, hot air to raise IAT readings and block air flow to the engine.  Hot air and low airflow equals less power.  This is why we developed our IAT kit years ago.  The flapper delete is just an add-on progression to the new model.  From scratch we developed block off plates and a whole new IAT relocation kit as the harness has changed from the 10-19 models.  All parts fit very snug and are made from billet aluminum for weight consideration and longevity.

The new airbox “flapper” design was made to reduce engine noise at low RPM’s.  Instead of the previous foam restrictor that we saw in the 17-19 S1000RR, the 2021 S1000R almost completely closes off the airbox in certain scenarios.  This lack of airflow leads to very high intake temperatures.  The ECU’s strategy is designed around this “heat soak”.  Timing retard is based on a “per gear” and “per RPM” strategy and will not taper off until higher gears due to the airflow and RPM needed to open the flappers.  This is vastly different than previous years and more similar to the BMW GS1200’s (which also benefited greatly from this kind of relocation).  The first half of the throttle angles (0-50% throttle, commanded) and first three gears are heavily timing retarded on the stock calibration.  This is due to hot and stagnant air that sits in the airbox while the flappers stay closed.  The design of the OEM flapper servo creates an unnecessary bottleneck of airflow inside the airbox at higher speeds.  This distributes air to the inner most cylinders, negating performance and the maximum “ram air” effect the factory airbox can provide.

Our first kits have been installed and successfully tested with positive reviews on the street and track!  The bike doesn’t feel as lazy from a dead stop anymore.  The induction noise is superb after the installation/removal and compliments the essence of what a S1000R should sound like.  The IAT Kit allows for consistent power at all RPMs and gears instead of waiting for higher gears to get additional, rated power.  During our testing on the dyno and per gear / per RPM datalogging, we found many delays in the factory ignition to combat the heat soak the factory airbox flappers create.  With our flapper delete and relocated IAT sensor, the bike reacted sharp from a dead stop and in lower gears / speeds (pre-6000 RPM cruising) without knock detection.

Getting a true ambient temperature from the front of the bike is much better than getting temperature readings from its original location on top of the engine with the flapper doors shut.  Idling at the starting line, pits or at a street light on a 100 degree day will put the bike into a temperature protect mode and pull power out to “save itself” until the IAT sensor reads accurate ambient air temp once the bike starts moving.  True ambient temps help the bike deliver more power and stay consistent in racing conditions.  We are not tricking the sensor but simply allowing it to read proper temperatures of the outside air.


      • Relocates the Intake Air Temp (IAT) sensor and removes the airbox “flappers”.
      • Moves the IAT sensor from the factory location near the cylinder head to the front of the bike to get a true ambient reading.
      • Removes factory airbox flappers to allow fresh air to enter the airbox at any speed, RPM or gear.
      • A true ambient reading means more power but also means consistent power.
      • Noticeable improvements in stop-and-go traffic, starting a race from a stop and exiting the pit.
      • Even distribution of air to all cylinders without any cylinder bias.
      • More air to the engine with plastic flappers removed.
      • No downside and dyno proven gains across the powerband (see dyno chart below).


      • Stage 2 Flash With Airbox Update To Maximize IAT and Flapper Delete Performance
      • (1) IAT Extension Harness
      • (1) Billet Aluminum Plug For Original IAT Sensor Location
      • (1) Flapper Servo Block-Off
      • (3) Billet Aluminum Plugs For The Airbox (Two Small and One Large)


You can see that while Stage 1 has a large gain over stock, our Stage 2 has a greater gain.  Peak gained 4whp over Stage 1 but the mid and low-range of the RPM band gained huge.  This is where you’ll be riding your motorcycle, mostly, and this is where the largest gain is.

BLUE LINE = BT Moto STAGE 1 (159WHP / 82WTQ)

**Testing performed with 93 octane pump gas. Usage of a lower octane will yield lower overall power.**

Affirm Financing


This video demonstrates the difference from factory stock, Stage 2 with intake flappers open only and Stage 2 with intake flappers open with IAT kit for the BMW S1000RR (same effects on S1000R).  This is the exact same motorcycle in all videos with temperature comparisons, showing the effectiveness of both the kits working together.



Thoroughly tested by our own engineers, not just for its function but also durability.  We purposefully dropped this thing about 100 times just to make sure if you accidentally dropped it, it would still be a usable device.

So why buy it when you can just send in your ECU for flashing and spend less? Let’s see the breakdown.

NO DOWNTIME – No need to send in your ECU or remove it from your bike at all.  You order the handheld, it get’s delivered to you, you flash your bike.  You never miss a day of riding and no effort removing the ECU.

STORE MULTIPLE MAPS – When you send in your ECU, you only get one map.  You might be thinking, “why would I need more than one map?”.  Storing multiple maps means you’re able to flash for different fuels.  If you’re a serious track competitor, we can work with you to get you different mapping for different tracks.  If, for example, you’re add an exhaust to your stock bike, we can email you a file that takes the new exhaust into account with the changes you need to optimize your bike’s new modifications.

GO BACK TO STOCK ANYTIME – Not only can you store multiple race maps, you can also flash the original, stock file back into the bike at any time and for any reason.


Additional information

Weight 15 lbs
Dimensions 15 × 15 × 15 in


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  • “ Bike is running awesome and no out of the ordinary popping under load during downshifts at high rpm. My hats off to your team for making me feel like I have a personal tuner at my disposal. Really appreciate the quick turnaround to get me straight. I can definitely feel the extra power! ”

    Andy Young - Maryland Aug 28, 2018
  • “ This product is amazing.  I feel like I have a better version of my bike.  Like it should have come this way.  The throttle smoothness and even power band make it a joy to ride.  I no longer feel as if I'm riding a wild bronco lol. Thank you again, I didn't think that a L-twin could behave this well.  Also, your customer service is the best.  I could always reach you by email or phone.  I will tell everyone I know about this fantastic addition.  Keep up the great work, guys! ”

    Dan Martinez May 01, 2017
  • “ I have a 2015 S1000RR and was extremely skeptical when I heard about BT Moto and the power they got out of an ECU flash.  After speaking with the team at BrenTuning, all my hesitations were put to rest and I haven't stop winning first place trophies since! BELIEVE THE HYPE! ”

    Troy Gleason - California Jul 10, 2016
  • “ Bren and his team did an awesome job on my bmw s1000rr. Went from 179rwhp an 83 rwtq to 206 rwhp and 93rwtq. Customer service was great and I highly recommend them for any of y'all that want to make that power!! ”

    Paul Jackson - Texas Jul 10, 2016
  • “ Purchased the tune for my 2015 BMW S1000RR. Was skeptical at first and initially had a bunch of questions. Chris was very patient with me and answered them all. Had some problems after receiving my ecu back and Chris was very helpful in getting all my issues worked out. Bike runs fantastic. Definitely worth it. Thank you again guys for dealing with my questions and taking care of everything before and after the purchase. Fantastic customer service. ”

    Cody Hunsucker - Tennessee Jul 10, 2016
  • “ After doing some research it was obvious that BT Moto was the best option for tuning of my S1000RR. I wont go into details but after multiple overnighting of parts to me at no additional charge, I'm really impressed and satisfied with the end result and I haven't even tried out my race fuel tune yet! To top if off I received a random care package of goodies from Chris today. The customer service at BT Moto is probably the best I've received from any business I've dealt with. Their email response times are unreal as well, lol. Literally sometimes instantly, kinda weird. lol. I would recommend any and everyone to BT Moto for your S1000RR tuning solution. If anyone has any questions or are hesitant before purchasing, feel free to shoot me a message and I'll help / assist / give you a more detailed opinion on my experience as well. ”

    Trey Hull - Texas Jul 10, 2016
  • “ I have the Bren Tuning ECU flash on my 2015 BMW S1000RR and it is unbelievable how fast this bike is. This tune is the best thing I got for my bikes. I have also did the Bren Tune for my 2014 BMW S1000r for which it just made this bike really nice. Bren Tuning is the best. ”

    Darnell Edwards - Maryland Jul 10, 2016
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