It was a fair mount of work, especially when you do it twice. Ugh. I made the first on without the intake on the car. I wanted it to be rotated level, as opposed to on an angle like some of the commercially available adapters. Well, the throttle arm wouldn’t move because it was hitting the “triangle” on the timing cover. I had evenly centered the 90mm hole over the intake 85ishmm hole the first time. The second one, I lined up the bottom and “blended” the larger hole to the smaller on the intake. You can see it in the photo. I’ve cut out much more since then even on the intake side of it too. It had a strange whistling noise initially. It’s just about gone now.