The photo-realistic CAD rendering looks much better than the real thing. The sealing surfaces on both sides were very poorly finished. On the first attempt to install, it leaked very badly, made a lot of sucking noise and the engine would barely stay running. I resurfaced the sealing surfaces on my milling machine. The surfaces were so messed up that I needed to machine approx .040" off each face to get the face flat. Now it seals up OK and the engine runs fine. I haven't had it on long enough to know about any MPG gains.
It uses a gasket between the spacer and the throttle body. I do not recommend that. There is a reason for the o-ring style rubber seal that is between the throttle body and the intake manifold. I recommend paying a little more for your throttle body spacer and getting one that has a groove machined in the face for the same type of seal that fits into the top of the manifold. You will get better sealing without having to risk damage to the throttle body because of the silly 3-bolt mounting. The throttle body should have a 4 bolt mounting, but there is nothing we can do about that.