Boost drop in higher gears?

[alundra]

So I still have trouble.
Yes 12psi will be my goal, it sufficent for me .

I'll check my car to find something later.

Some hints for reflexion: I'm at 3rd gear around 2000rpm, stabilize my cruises. When i went full throttle, it goes 1B and drop to 0.6 (spike appeared) but when i reached 0.6, when i upshifted, no problem it went to 0.6 and maintained the boost until 5800/6000 rpm.

I tested in 4th gear same thing, 2000 rpm, full throttle, spike appeared too

According to me: perhaps I have a leak hided, the spring of MBC is not enough hard,...

Thaks for all