Can't boost more than 5psi. Car runs fine otherwise.

[airjawed]

Well after disconnecting the line from the N75 to the WG, I was able to build more boost, so I do have a bad N75. The S6's must have been incompatible. Now I just need to figure out why it's running rich.

How much boost is it making now?

[s4oak]

Well it builds indefinitely since the wastegate is permenantly closed. I got it up to 15 before easing off the throttle.

One question I still have: Does disconnecting the N75 hose mean it's definitely a bad N75 or could the car be in limp mode over bad EGTSs and disconnecting the N75 is just bypassing the ECU's decision to run limp mode?

[airjawed]

Well it builds indefinitely since the wastegate is permenantly closed. I got it up to 15 before easing off the throttle.

One question I still have: Does disconnecting the N75 hose mean it's definitely a bad N75 or could the car be in limp mode over bad EGTSs and disconnecting the N75 is just bypassing the ECU's decision to run limp mode?

Your intuition is correct. You may have either a bad N75 or the ECU is in limp mode. Unplugging it does bypass things but does not tell you anything for sure. If you drive while easing into the throttle does it run well? If so that leans towards a bad N75 in my mind.

Have you tried to blow into the long connector at the N75 while it is unplugged from the electrical connection? It should not allow air to blow through if memory serves me correct.