i am running a rb20det i have

stock intercooler
turbo x s boost controller
hks waste gate
garret turbo 70 front and a smaller back

when i go on boost in any gear the boost goes up and then goes back on vacuum until i change the gear
the point were the car is just about to start using the power it cuts back.

i have checked for leaks on the intercooler, the piping and found no leaks

help me please i dont know if its the waste gate the timing or if the car has a boost sensor that cutting it back

 

What are you using to control the air/fuel mix ? .... I'm no skyline expert... but I'm assuming the air/fuel mix is controlled by the PCM on a stocker.....which means if you added a boost controller and wastegate and bumped up the boost the PCM is seeing that and pulling timing because it's seeing that you are about to overboost.

 

i got through i was leaking boost on the turbine one of the bolt holes