Help - Boost Loss

Hi all,

i recently had my car mapped (sports car/ fuel pump/ induction kit) fitted as part of the package and the past few days I’ve noticed sometimes I get little boost when putting my foot to the floor.

it only lasts a minute or so and then I get full boost back (sometimes a little jerky when coming on boost) 

it still revs fine and sounds healthy but just seems down on power all the way through the Rev range and then picks back up again.

Any thoughts on what it may be?

Car is a 2010 WRX-S 

Thanks

Matt