Street Friendly (And California Legal) GD Subaru STI Build! Part Three, Getting Some Green Power With Cobb Tuning

The intake tube is reinstalled.  It’s not in the instructions but you can cut out the back of the tube so its cold ram air can exit right into the airbox!  Since the engine’s flow characteristics are changed with the intake, it is recommended that the engine is run with a Cobb OTS (Offf The shelf) CARB-approved tune for the intake and exhaust.  With this tune, the car will be fully smogged legal, even in California!

To tune the car, we used Cobb’s Access Port. The Access Port can be used to reflash the car’s ECU with Cobbs Federal or CARB-legal tunes downloaded from the Cobb website.  Cobb Pro Tuners can also use the Access Port to fine-tune these tunes to make up for car-to-car variations.

The Access Port comes with a cable to connect the Access Port to the car’s ECU via the OBDII diagnostic port.

The Access Port comes with a basic mounting bracket,  other optional mounting solutions are sold through Cobb.   The Access Port can also be used to read and reset check engine codes after repairs. It also makes a handy gauge for ECU functions and can data log to help Pro Tuners diagnose tuning issues.


  1. I know there was a lot of complaining when Cobb decided to pull a lot of their parts recently, but I’m excited to see what they can do while still being CARB compliant, especially with Flex Fuel and down pipes. Hopefully this owner decides to do more if/when the Project Green Speed development is fully fleshed out so the readers can get a no BS article about what is and isn’t possible while following the rules. As dumb as they sometimes may be…

  2. Thank you for the great article. Do you have any recommendations for an aftermarket turbo intake duct? There are a number of options on the market. I’d love to know what your experience has been with them, which is your favorite, and why.

    It looks like the resonator chamber had already been removed from the fender. Cutting out the back of the air intake duct, as mentioned on page 9, seems like a good idea, especially if the resonator is gone. But, wouldn’t you also recommend blocking off the two giant holes in the inner fender wall which, without the resonator in place, expose the air cleaner to all the road grime blowing past the fender liner?

    Thanks again for the excellent content!

  3. I see you used the COBB titanium cat back, is this similar to the older COBB catbacks that neck down to 2.5′ at the area that mates to the downpipe, or would this be a true 3′ all the way through?

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