@Modular Racing - I assume for the spacer you actually need 2 gaskets correct? 1 between the heads and the spacer, and 1 between the spacer and the plenum correct? That's what it looks like in your picture from the OP.
@Modular Racing - I assume for the spacer you actually need 2 gaskets correct? 1 between the heads and the spacer, and 1 between the spacer and the plenum correct? That's what it looks like in your picture from the OP.
I'm going to answer my own question. The answer is 'yes' it requires 2 plenum gaskets. It's Ford part # XR3Z-9E436-AC. I installed the spacer over this past winter with the Accufab TB, 90mm MAF from Ford Racing and a new tune. I'm pleased with the performance. No I didn't dyno so I don't have numbers but for what I paid I'm happy. It also gave me a chance to clean the upper intake which was super dirty. Hardest part was getting the EGR tube to stretch and reattach but it's possible and I did it. You can buy the spacer at Summit Racing, Jegs and others for about $99.