Boost control with simplified sequential
 

With the Adaptronic Modular, do I need one or two MAC valves to control boost on the stock sequentials? Haven't found a clear setup or answer for this.

Anywhere from zero to two. If you have your oem solenoids that are in working order, you don't need a MAC valve. If you want to replace the boost control solenoid, then you need one. If you want to replace the boost control solenoid AND the pre-control solenoid, then you need two.

At the moment I am only hitting just shy of 8psi. Gear doesn't seem to matter. I have gone into the Boost Duty Cycle Map and nothing I do in there seems to make any difference. I have tried 0 across the board and I have gone up to 60 and had no difference in boost levels. Any suggestions on where I should start looking?

Try going up higher. The stock system is pretty unresponsive up until a certain point. The three port solenoids should also run around 35Hz for the frequency if I remember correctly. Polarity doesn't matter either so as long as your OEM wires are hooked up, it should be working. Double check for boost leaks as well. The twins like sitting around wastegate pressure with any little leak.