car keeps going into limp mode after the bigger turbo. i thought it was a tunning problem so got speedtuning stage 2 tune and it ran great. till i relized the n75 valve was not pluged in so i pluged it in got it up to 19psi and it kicked it down to 5psi now wont go over 5psi?!? all help is apprecated!!!

 

This is overboost protection. The ECM detected the car boost too much and so it triggered the N75 valve to stay wide open to keep boost to a minimum.

In a stock ECM...
If airflow (detected by the MAF) is less than expected, the ECM will close off the wastegate (increases boost) until airflow is at the expected amount. If this is never achieved by the time the max boost limit is reached, overboost fault is set and the N75 valve goes fully open allowing the wastegate to open at it's minimum level of boost, 5 psi.

Unplug your MAF and try driving it... see the boost shoot back up? Clear your faults to get it out of the limp mode.

Your tune likely caused this situation, you're probably going to need a manual boost controller or something to make it work.