boost fall off uptop?

[turbo2nr]

we i noticed in 2nd (auto transmission) my turbo will spool up like normal , but around 6k boost will taper off to around 5-6 while around 4500-6000 it will hold 8psi..

im wondering why its tapering off up top. this turbo is stupid big and never looses boost up top. (62-1 t4 back) it would always pull hard up top...

my guess is possible a vacume leak or a transmission problem not loading it up top. as soon as i put it into drive it shoots up to around 8-9psi... and holds it...

my turbo should be ok? its not signs of the turbo going is it? i mean it spools up the same, its just around 6000 6100.. could it be because its out of the efficency range of the cams? i know the power falls up due to maxing out flow around 5500rpms......

im lost help plz

[neverlift]

sounds like a boost leak. is the setup blow thru? have you checked your connections? chances are if the turbo was fine, it is fine. now maybe if the transmission is slipping but I see it spiking then.

[icnuthin]

definitely a boost leak and if you are not careful then you are overworking your turbo. but go through out your piping and check all couplings and your hoses to your intake.