what can casue the loss of my boost spike...?

when stu set it up it spiked at 1.9 bar and then dropped back and held 1.5 bar - went like fook, its gradually gone over the last 6 months or so, with not drivnig the car hard much ive not noticed it missing as it havnt been booting it about, went out the other night and it seems quite laggy one its rolling now, like when you are above 4K and change gear there is literally (it feels like) a couple of seconds before boost is back to the level it was, it seems to come in very progressivly and only up to 1.5 bar, no spike and not any where near as savage as it was when it was first done, any other obvious things to check - it had a new -34 and 3 bar map sensor fittd at the same time it was set up, can the newness wear off the -34's and need more pre tension after they've ' bedded it' ? i havent touched anything else other than new oil and plugs (which are the same type as when it was set up.....

 

boost leak? in which case, be careful not to overspeed the turbo

 

weak actuator.....

 

as the posts above, or maybe the wastegate penny isnt seating correctly anymore and has gradually got worse over time - or even cracked!!

 

think ill have to give it a coat of looking at, bearing in mind the actuator is ony 6-9 months old now... but i suppose they can still fail in that time..