The rotor is the 04 STi, so its the 326X30.
Yes, I will measure that when I get home today. I have some 17" Rota Torque's on their now and you can see the clearance is pretty close. I am going to try to see if I can squeeze 16" subie wheels on it so I can eventually run gravel tires. I'm hopeful but somewhat doubtful from what I hear on the forums. Although the UCF30 caliper might be "dimensionally forgiving."
That thread engagement was my very concern from the beginning. However I did the calculations and it meets the full thread engagement length requirements, that's why I went ahead with the dog bone design. (I believe it was .59"?) The alloy is just tapped, no insert. If there was an insert, the minimum thread engagement for the insert would not be met. So as long as you are careful bolting everything up and don't strip the treads, you'll be good. You don't have to remove the caliper to change the pads obviously. Oh and remember, the tensile loads on these bolts is very low and I believe the stock UCF caliper bolt threads into an Al upright also.
I have already put about 300 miles on the setup with some mixed semi-aggressive canyon runs and I am very pleased with the setup so far. It really stops. The increase in thermal mass and Aluminum caliper really improves the heat dissipation. And no joke, I think this caliper is lighter than stock!
The dog is actually a Pitbull Dalmation! He is the most well mannered dog I have ever had, let alone met.