Mine has the same problem but sometimes it happens all the way through to 3rd gear, its really annoying as sometime i pull out to over take and nothing happens and all i get is a slow and sluggish overtake, but then sometimes it will come on line, but mor offen than not i dont get any boost from tubby two in 1st gear.
Ive put mine down to the actuator which i am soon to replace, i have checked all of my VSV's and they are fine, im going to check that there is no presure drop across the intercooler. To see if i can get to the bottom of the problem as it is starting to wind me up.
Oh and yes i do have a boost guage fitted and giving a reading of around 1.8 every time soon to uprate to 1.2 when i put my boost controler on.