I have the same issue in the morning I got 1.7 bar (sometimes 1.8 bar if it cold out) in the day time it would go down to 1.6 I have same turbo, but GM Boost solenoid and Heavy Spring Actuator. So, its a Turbo or Actuator and not a Boost controler.

If you figure out how to make boost stable, please let me know. As 2 PSI difference since morning to afternoon drives me NUTS.

 

Well without the MBC it's slightly lower....

What has me stumped is this... If I punch it 2nd gear at 3000rpm I build about 21-22 psi and hold it pretty much til redline. If I punch it 2ng ear at 4200rpm I build almost 1.8bar (not sure what that equals off hand) Which is WAY to much for pump gas.

I'm going to check all my vac lines for leaks.. I know my IC pipes are fine. I'm also going to take some tension off the WGA. If all else fails I'll try to find a blue spring to put in the forge WGA or just buy an EVO9 stocker.

 

Well no leaks unless if things are leaking when the engine is really hot. Still need to take soem preload off the WGA to see if that helps some. Still spiking almost 25psi (1.7bar) with only the WGA (no mbc).

 

Ok so taking some of the preload off the wga arm helped out a lot... I think it's just a hair too loose now... getting a lil creep in mid to upper rpms.