mine had the same problem! spent ages trying to track it down cause the previous owner had MARKED them backwards, i assumed that meant it was right the way it was
anyway it wasn't until i found a few other broken hoses and got a valve off bazza that it all started working properly
linz i know the feeling you mean, it does it to me sometimes in first gear if you back off on the throttle then apply it again, kinda looses boost then has to spin up again before its go go time
