First of all you will need a stock sun gear cover for the front drum because ATS machines theirs down to fit 7 clutches. I suggest buying a complete clutch kit from either Suncoast or PPE which will give you all the machined pressure plates and proper clutch clearance.
ATS does use the Transgo trim valves but they do not drill the holes in the seperator plate. If you are using the copilot do not drill the plate. I also don't like the hollow pressure regulator valve ATS uses and suggest a stock valve. You can continue to use their pressure regulator spring if you are making 600 + hp but I don't recommend it for a daley driver as it is too much. If you're going with a stock pr valve, you will need a modified Transgo converter flow valve so there is no pressure nockdown on TCC apply. I also recommend a different converter.
The above was posted by Mike L in thread discussing the same thing. My ats stage 2 lasted less than a year and I swapped to alto clutches and the only thing I did different than above aside from a few things in the valve body and pump was replace the bearing ATS uses when they machine the P1 drive flange.