Boost Question

hi i currently have a pd100 with a pd130 turbo and intercooler fitted its also remappd. my question is im having a problem with boost i believe, im getting an airy sound from the right side of the engine, sounds like a leak to me, what happens is sometimes when i put my foot down there is no real pull until i let go off the accellerator and then put my foot down agen, sumtimes once or twice and then it lifts as normal.

can any one tell me if it is a boost leak or anything else to do with the turbo. thanks.