When you say it builds slowly, at what rpms? is it consistently linear throughout the whole range? it should still peak like a gas turbo and flick up to max boost in 2nd and third.
It definitely doesnt "flick" like you say, or like in my gas car. It builds almost linearly. It seems to take forever to hit max boost in 3rd and 4th mostly. I am able to hit it in 2nd rather quickly, and in 5th as well.