Boost drop in higher gears?

[alundra]

Ok, I need some advice.

My mods:

Large air filter, piping in 2"5, intercooled, blow-off, cold spark, polished head, new valve guides+headgasket changed 8 months ago, healthy T2, full exhaust line 2"5, standard ECU management in 8 spark head model...

I fitted a MBC, i set up at 12 psi in 2nd gear at same rev in 3rd it dropped at 10, in 4th went to 8, sometimes 6 (not on cheap boost gauge, it's a TIM).

I rechecked all lines (air/oil/water) for leaks, only in steering rack...

What can be checked more?

Who went from MBC to EBC? Does a EVC can hold the same boost in all gears?

Thanks.