Home / 2003-2005 BMW Z4 MS45 ECU Tuning


We spent *years* perfecting our MS45 ECU tuning services with our in-house supercharged BMW Z4 and beta testers around the world. This has included:

  • Hundreds of calibration iterations
  • Extensive dyno tuning, including third-party dyno testing to independently verify results in every climate
  • Thousands of miles of road optimization
  • Partnering with the world’s most committed software professionals to provide a premier end-user flashing solution - Severn Tuning's FlashApp!

We have achieved the absolute best MS45 tuning solution, bar none! Our ECU tunes are in a category of their own.


Over the years we have advanced our tacit and explicit knowledge of the more than 5000 parameters in MS45, and we appropriately apply modifications specific to your setup. Simply put, an engine is more likely to be limited by its hardware than our software. Please see our customer photos - the results speak for themselves!

Our FAQ - MS45 page provides details the tuning process, what to expect, and information on our FlashApp tuning software.

Stage 1: This is our “OEM plus” tune, ideal for a naturally aspirated engine with modifications ranging from stock to full bolt-on. Expect approximately +15 horsepower on a completely stock car, and more with additional modifications. Full- and part-throttle tuning is optimized through adjustment of VANOS, ignition timing advance, engine torque request, throttle response, lambda targets, DTC delete (as required) and other proprietary revisions. Despite targeting naturally aspirated vehicles, our Stage 1 ECU tune incorporates more parameter changes than most tunes included with aftermarket forced induction kits.

Purchase Stage 1 ECU Tune

Stage 2: Ideal for major power-adders such as forced induction. Our Stage 2 ECU tune can also benefit naturally aspirated race engines making >20% more horsepower than standard through modifications such as large-duration and high-lift camshafts, individual throttle bodies, and head work. Stage 2 includes the same parameter revisions as Stage 1, plus additional modifications to injector correction factors, intake manifold models, torque limiters, engine torque calculations, and other proprietary revisions. When supporting hardware modifications are installed, power gains are 50-70 horsepower beyond standard forced induction kits. Stage 2 supports up to approximately 400 bhp / 350 whp and the use of water/methanol injection, intercooling, and flex fuel (with the AFD ProFlex Commander, sold separately). Please note that turbocharged cars are required to have certain hardware modifications installed. Quality injectors with known injector data are required. Contact us for details.

Purchase Stage 2 ECU Tune

Stage 3: Specifically developed ECU tuning for vehicles making over 400 bhp / 350 whp, or engines utilizing a blow-through aftermarket mass airflow (MAF) sensor. Stage 3 includes the same parameter revisions as Stage 2, plus additional modifications to the ECU’s program code to support a high-flow MAF sensor as well as sensor scaling. Stage 3 is recommended for cars with ‘built’ engines, including customers seeking a TS3 setup for MS45. Our Stage 3 ECU tune is the ultimate MS45 tuning solution, developed specially for the most serious customers!

Purchase Stage 3 ECU Tune

Alpha-N: We are the ONLY tuners which can offer forced induction Alpha-N tunes for MS45. With an Alpha-N tune, the MAF sensor is eliminated, and load is calculated based on throttle plate angle (Alpha) and engine rpm (N). The advantages of alpha-n tuning are: background compensation tables are bypassed; internal ECU airflow and load limiters become irrelevant; the tuning process is streamlined; and maximum engine power can be extracted. This is why nearly every aftermarket supercharger kit for naturally aspirated BMW M cars uses Alpha-N, and our development of high powered M cars has led us to expand our offering of high quality Alpha-N tunes to MS45 owners. Tuning an ECU to run in Alpha-N mode requires extremely precise mapping which other tuners simply are not capable of!

Purchase Alpha-N ECU Tune

Additional Tunes: Three additional tunes can be purchased for $500. Examples include normal/high boost, summer/winter, high/low altitude, pump/race gas, E85, OBD2 monitoring on/off.

EWS Delete: We are one of the few that offer EWS deletes for MS45. Commonplace on race cars, an EWS delete allows for "hot swapping" ECUs. Customers can have multiple ECUs with different configurations and switch between the ECUs at any time. Please note that EACH ECU requires an EWS delete modification at $200 per ECU. We cover return shipping.

Purchase EWS Delete

Handheld Flash Tuner: Some customers desire the ability to flash between tunes without taking a laptop with them. Our handheld, touch screen flash tuner ("programmer") stores up to five tunes which can be flashed to the vehicle's ECU in approximately two minutes. Our Stage 1/2/3 and Alpha-N tune purchases include a FlashApp license, so this purchase is NOT required in order to reflash the ECU and is offered as an additional add-on. 


Customer Loyalty

When upgrading between each stage of tune, customers are credited for their previous purchase and only pay the difference in price between tunes. For example, if a customer has already purchased a Stage 1 ECU tune and wishes to add forced induction, the customer will only pay $300 to upgrade to a Stage 2 ECU tune.

Disclaimer - Flash tuning is separate from coding and diagnostics. It will not solve underlying mechanical or electronic issues, and in some cases, it can make problems worse. We highly recommend you consider tuning to be a final ECU calibration and the very last step when optimizing your vehicle. Recommended for off-road use only!

More Info / FAQ