Project GD STI, Fixing all the Details!

Everything is pretty tightly packed into our car’s engine compartment.  If you know these cars, you know that Subarus of this era have pretty messy wiring and plumbing.  We put some effort into cleaning this up and it shows.

We are pretty proud of our OEM plus style of tuning and setting up, our IAG engine looks almost as if the Subaru factory had a higher performance model with an optional engine!

Stay tuned, next we will be tuning and dialing in our new motor with help from Church Automotive Testing.



Cobb Tuning


CSF Race

MeLe Design

Antigravity Batteries

Process West/Rallysport Direct 



  1. I don’t think you are correct about the surge tank being mounted higher than the factory one. It’s mounted lower than the top of the cobb AF box and the stock is mounted almost level with the top of the intake plenum.

    It looks nice no doubt but it’s not higher than the stock one.

    1. We had a stock STI in the shop that I could actually measure and you are right, the top of the OEM tank is higher. The bottom of the IAG tank when the hoses attach is higher than the OEM tank bottom. The main reason we used it is to clear the process west intake manifold. Thank you for pointing this out and I edited the story to reflect this.

  2. Hi Mike!
    Do you think the lack of increased NVH from the IAG mounts maybe because of the increased chassis stiffness from the Cusco bracing? It would be interesting to test this out with and without the braces.

      1. Apologies, I did not mean for you to test it yourself, as I am aware you must have a busy schedule. I was just thinking out loud as that would be an interesting data point to test in the future ( possibly by me ). I do appreciate theses awesome articles you and your team have put together for free and I am building my STi very close to your build which is why I love to geek out on this stuff 🙂

Leave a Reply

Your email address will not be published. Required fields are marked *