A couple observation I made while swapping in the SVT UIM last weekend:
1. First off, the SVT UIM is a completely different casting from the stock one, just FYI. It's not a modified stock one.
2. The TB side of the SVT one has a smoother interior wall....but on the exit side, the finish is sandpaper-like and is covered in overspray from the black powdercoat. It confuses me how or if extrude honing was done.
At first, I was actually saving the UIM for a future engine build, but when I had everything apart for cleaning, I noticed the SVT ports EXACTLY matched my stock LIM ports. The primaries on the stock UIM looked puny in comparison (27mm to be exact).
And yes, the UIM to LIM gaskets are big, 35 and 36mm, just adding numbers to what Brad said.
