Project GD STI, Fixing all the Details!

We also ran IAG’s plumbing kit.  This works with the IAG fuel pressure regulator and fuel rails.  It’s plug-and-play with no fitting, cutting, or messing around.  These parts save a ton of time.

We replaced the stock surge tank with IAG’s surge tank.  We had to run this because the larger plenum on the Process West intake manifold gets in the way of the stock surge tank.  We had to slightly modify the airbox of the Cobb SF intake to make room for it.

Our new CSF radiator has a thicker core than our previous Koyo radiator.  It drops right in with a perfect fit.

Our Mele battery box and Antigravity ATX30 lightweight battery fit perfectly and make some needed room in the engine compartment.  We wrote about it before but this combination shaves over 30 lbs from high in the front of the car to make a feelable difference in handling.

We replaced the thin plastic Greddy overflow tank that we had to install to make room for our front-mount intercooler with this fabricated aluminum tank from Cobb.  This is a more compact, durable, and attractive solution than the Greddy part we had before.


  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 🙂

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