Boost spike with a Qboost - is this normal

[robk46]

I hooked up a Qboost controller to try it out. I set the screw so I get 15# of boost, but it spikes to 17-18# for some reason when I launch. The car has a stock turbo, non-adjustable stock wastegate, stock intercooler. If I use the stock solenoid, I get a rock steady 15# of boost. Is this just the nature of this type of manual controller? Also, when I was poking around on this board and the other ones, some folks say they have a small hole drilled in the body of the Qboost controller. There is no hole drilled in the new one I just bought.