Subaru WRX STI Type RA Accessport and Parts

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Support for Subaru’s newest version of the STI is now available!  The 2018 WRX STI Type RA is the limited edition car Subaru enthusiasts have been waiting for.  Upgrades over the standard WRX STI make it a true weapon on the road course, inspired by the 2017 Nürburgring record-setting car.  Well, the fastest ever just got faster.  Our Subaru team is extremely pleased to announce Accessport and Accesstuner tuning support as well as assorted bolt-on parts compatibility for the 2018 WRX STI Type RA!

Subaru Accessport V3 (SUB-004)

ap3-sub-004-ra The Accessport is the world’s best selling, most flexible, and easiest to use ECU upgrade solution for your Subaru.  Unlock power hidden within the vehicle by replacing conservative factory settings with more aggressive calibrations.  Follow our staged upgrade path with pre-loaded Off The Shelf (OTS) maps or use custom mapping for any modification level. It’s the last engine management solution you’ll ever need.

Get yours HERE!

Off The Shelf Maps and Power Gains


The Type RA is loaded with a much more aggressive tune than we are used to seeing from Subaru.  In fact, on ACN91 octane fuel the car was seeing enough knock to shut off the boost control system completely.  Using higher quality fuel (93 Octane) we did see much more consistent power out of the Type RA however it is still leaning fairly hard on the knock detection system – with hits of 4 degrees seen relatively consistently.  With that said, our internal calibration team was still able to find a bit of power, specifically in the mid-range, which can be realized in our Stage 1 Off The Shelf Maps.  By using a different tuning strategy, we were also able to mitigate the concerning levels of knock.  This makes for noticeable gains and peace of mind, especially for those using ACN91 fuel. Our Calibration team will be investigating additional Off The Shelf Maps (Stage 2, etc.) in the future.  Stage 3 Packages will not be available until we have a solution for the airbox snorkel, more on that below.

STI Type RA Typical Stage1 vs. Stock Power:
Stage 1 93 Oct. Max gains: +16% HP / +17% TQ
Stage 1 93 Oct. Peak gains: +2% HP / +14% TQ

For additional information relating to Off The Shelf Maps, see the Map Notes Page.

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2018 Subaru WRX STI Type RA – Part Compatibility

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Almost all of the parts from the standard 2018 WRX STI carry over to the Type RA with the main exception being the SF Intake System.  While the intake and airbox will physically fit, the STI Type RA comes with an updated intake snorkel that is not compatible with our SF Intake Airbox.  Due to heat concerns, we do not recommend installing an intake system in these cars without using an airbox to direct fresh air onto the filter element.  Our hard parts team will be evaluating a Type RA-specific Intake Airbox to go along with our SF Intake in the near future.  The COBB SS 3″ Turboback Exhaust does bolt right up to the STI Type RA as expected, however, a Stage 2 Off The Shelf Map is not yet available.  Custom tuning will be required for any bolt-on parts at this time.

For a complete list of compatible parts, see the 2018 WRX STI Type RA Vehicle Page.  Wondering which Subaru models we support? Check out our entire selection of Subaru aftermarket parts.




Benjamin Wilson on May 15, 2018 says:

Can you give more detail on why Subaru is leaning on knock detection so heavily, even on 93 gas? Isn’t that going to be disastrous for stock RA longevity? What was the ‘different tuning strategy’ used to try and correct this?

    Marshall on May 15, 2018 says:

    Sure thing. The factory calibration essentially starts with higher base timing values and the knock system rarely allows it to fully take advantage of dynamic advance. Our calibrations will start at a slightly lower base value with a higher allowance of dynamic advance. It’s not necessarily disastrous for longevity as the knock correction system is indeed doing its job. Our approach is to not lean on that system as hard as the factory calibration does.


Hunter Hobgood on May 15, 2018 says:

Is there any difference between any of the stages for the STI Type RA maps versus the STI Limited maps, regarding HP and TQ curves, peak numbers, etcetera?

    Marshall on May 16, 2018 says:

    Hey Hunter! We have not been able to do a back-to-back comparison on the dyno but have a decent idea of how things would shake out. With good fuel in the tank, the RA may make a touch more power than the STI in stock form. Both cars will make almost identical power with a Stage 1 tune. Since it does have a slightly beefed up motor, our calibrators may allow the RA to make a bit more torque than the standard STI with subsequent (Stage 2 and beyond) OTS maps.


Joshua Detorie on July 5, 2018 says:

Any updates on the intakes and possible different stages? I’m getting a 19 Sti and it seems it should have the same layout but not sure.

    Adam Hill
    Adam Hill on July 5, 2018 says:

    Hi Joshua,

    We’ll have to wait and see once we get an MY19 car in our mitts. I assume a decent amount will carry over from 2018, but we’ll definitely have to do some dev work to flash them then test parts. Stay in touch for updates later this year.