Porsche 718 Cayman/Boxster GTS 4.0, GT4, Spyder 4.0L Tuning

We allllll remember when Porsche introduced the 718 platform with two small displacement turbocharged 4-cylinder power plants.  Uproar. Blasphemy. Turbocharging is cheating. Give us back our naturally aspirated engines and smooth power bands! While the team here at COBB was excited about the tuning potential of the turbocharged 2.0L and 2.5L 718s, we wholeheartedly agree that the song of a flat 6 is hard to beat.  Luckily, Porsche listened and shoved one of their best N/A motors to date right smack in the middle of a chassis that is more than capable of handling it.  The 718 Boxster/Cayman GTS 4.0, Cayman GT4, and Spyder come equipped with an all new 4.0L motor which, surprisingly, has great power left on the table.

We are extremely excited to announce 50-state legal tuning support for these cars by way of a new Accessport, the POR-015.

Applicable C.A.R.B. EO Numbers:

Vehicles Included

  • 2021-2022 Porsche 718 (982) 4.0L Cayman/Boxster GTS USDM
  • 2020-2022 Porsche 718 (982) 4.0L Cayman GT4 USDM
  • 2020-2022 Porsche 718 (982) 4.0L Spyder USDM

The Accessports

There are three options for Accessport tuning on these vehicles.  The primary decision is based on the support of PDK transmission tuning, the base part number (AP3-POR-015) offers ECU tuning only and can be used on either a manual transmission or PDK transmission car.  Our AP3-POR-015-PDK version of the Accessport comes offers both ECU and PDK tuning.  The third option can be used to add PDK tuning support to the base part number if PDK tuning is not desired or needed at first.

Engine Tuning

With these cars all sharing the same 4.0L power plant, tuned power output ends up being the same.  Baseline runs are shared between Spyder and GT4 and come in slightly higher than that of the GTS due to Porsche’s factory tuning differences.  Full details for each calibration can be found on our Map Notes Page, but we know you’re really here for the power numbers below.  Also of note, the GTS cars are able to take advantage of additional RPM.  We have moved their redline up from 7800 RPM to 8000 RPM, now matching that of the Spyder and GT4.

Engine Map Files Included:

  • Stage0 (factory tuning data)
  • Stage1 91 OCT or 95 RON
  • Stage1 93 OCT or 98 RON

Spyder/GT4 Power Gains

Boxster/Cayman GTS Power Gains


PDK Transmission Tuning

Transmission tuning has become ever popular for our supported Porsche vehicles.  With some tweaks to shift schedules and the implementation of a few custom features, the behavior of PDK-equipped cars becomes much more lively.

PDK Maps

A selection of three maps are available to to be flashed to supported PDK equipped 718s.  These files are included on the Accessport and can also be downloaded from the Maps Section of the COBB website.  For the Boxster GTS and Cayman GTS maps with and without ‘creep’ enabled are available for OEM+, Sport, and Aggressive.

For more details on each, visit the PDK Map Notes Page.

  • COBB OEM+ (GTS – only)
    • This file retains the OEM shift schedule with quicker shift times as well as enabling Race Start and Dual Paddle Neutral Custom Features.
  • COBB Sport
    • This file utilizes a slightly more aggressive shifting schedule and quicker shift times with both Race Start and Dual Paddle Neutral enabled.
  • COBB Aggressive
    • The quickest shifting time and most aggressive shift schedule with both Race Start and Dual Paddle Neutral enabled.

Shift Points by RPM

Shift Points by Speed (MPH)

Custom Features – Race Start, Decreased Shift Time, Dual Paddle Neutral

The ability to custom tune the PDK transmission in these vehicles allows for some of our COBB Custom Features to be implemented.  The two main features highlighted here are Race Start and Dual Paddle Neutral being enabled for the GTS trim cars.  These features are, of course, standard on the Spyder and GT4 and persist through into our PDK Maps.

For more details on each, visit the PDK Map Notes Page.

21 responses to “Porsche 718 Cayman/Boxster GTS 4.0, GT4, Spyder 4.0L Tuning”

    • Hey Mike! We can help change the part number of your Accessport to be compatible with the 982. I believe the charges associated would simply be $150 + any difference in cost between the current and new art number.


    • Hi VJ! This support is currently specific to USDM vehicles. We can likely support your European car but would need to identify the ROM ID on the ECU first.


  1. How do you define Stage 1?

    My car has aftermarket Over Axle Pipes and Muffler. Do I need a special tune?

    What if I add BMC air filters?

    • Hey Scott,

      The included Stage 1 map files are intended to be used on an otherwise factory car. We have not done any testing with aftermarket OAPs and likely will not venture down that road as it certainly brings some potential emissions concerns into play. As long as the emissions components remain in place you would be able to have a custom tune created by one of our Protuners. The BMC air filters should be just fine.


    • For our purposes during testing, we kept the runs short to avoid bouncing off the rev limiter too many times. We probably logged several hundred pulls in this car per month. Since we had already achieved peak power by 7500 RPM, we kept it on the conservative side to keep the car safe. Once we have the car back from emissions testing, we can definitely give it a few full sends for a full graph! Even with a slight drop off in power, there are still benefits to having an additional chunk of RPM on hand.


    • Hey there! We are adding tables to control exhaust flaps into our Accesstuner Pro custom tuning software. While that control is not available in our provided Off The Shelf Maps, it will be via a COBB Protuner and custom tune.


  2. Perhaps I’m reading the graph wrong, but Porsche claims stock HP for a GTS 4.0 is 394 while the graph shows it peaking at roughly 340. What drives this discrepancy and should the graph be interpreted as relative? That is, should the mod be viewed as adding roughly 60 HP, implying output of ~455?

    • Hi Dave! Porsche (and most manufacturers) report their power numbers as measured at the engine whereas we measure power at the wheels. The difference you’re seeing is commonly referred to as “drivetrain loss” which is simply the amount of power that ends up “lost” through the driveline.


    • Hey Danial, the short answer is “no” as we do not intentionally hide anything during the Uninstall process. You can absolutely use the product while your car is under warranty under the assumption that a level of risk is indeed present. That said, we have had zero issues without our calibrations for these cars and don’t anticipate that changing.


  3. Hi Marshall, Given the engines are the same why the power difference between the GT4 and GTS? Is it cooling related?

    • Tuned, they make the same power. In stock form, the GT4 and Spyder get a bit more RPM up top allowing them to reach higher peak power compared to the GTS trim.


    • Hey Mel!

      Here is a chart that shows the gains for your Boxster GTS 4.0. Let us know if you have any other questions.


  4. I’m interested but debating extending Porsche warranty I have 2021 Cayman GTS. I don’t know much about the risks of tuning. Will the dealer detect the tune. Will it pass emission’s?

    • Hey David! There are certainly inherent risks associated to turning up the power output and that is true with any application. Luckily, Porsche does have a history of “overbuilding” their motors so there is plenty of overhead to work within. While the gains for these cars are impressive, we are definitely not pushing anywhere near the limits of factory components and are not aware of any failures on cars using our product. All of our Porsche calibrations are covered by C.A.R.B. Executive Orders and are legal for use in all 50 States. At the end of the day, we definitely recommend having an open conversation with your service advisor to understand their viewpoint on aftermarket tuning. While some dealers are less accepting, many of them love what we offer and even sell our Accessports.


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