Any advice appreciated as im

I have a wrx sti blobeye with a strange fault

the car is running 396bhp and has twin boost settings tuned by Andy F
recently had fitted a perrin pro boost soleniod & injen rd1200 induction kit
(car was then remapped to suit the mods by Andy well pleased with the outcome until the strange fault)

This is what happens in 5th & 6th gear when driving at 60mph when boost comes in the car seems to choke itself boost gets to 20psi then drops to 15psi.

This only happens when on the high boost setting in 5th & 6th gear
low boost setting perfect in every gear

On high boost 1,2,3,4 all fine no matter how much stick you give her

Its just one of these annoying faults i want to get to the bottom of as the car in my opinion is spot on build wise & tuning wise

I just find it really weird that it only happens in 5th & 6th gear

Thanks

 

Its probaly overboosting , sounds like in needs boost trim in 5th + 6th because its being loaded up

ant

 

Thanks for the info.