I have the same problem i believe its your manual boost controller.
Mine use to spike to 1 bar..
Have turned it down a fair bit, and only spikes to .9 bar which is alright. Car can handle it..
Btw there are no hoses going to your stock soleniod??
But now since playing around with the boost, i have to many flat spots in 2nd.. guess i need a tune!!!
edit:
I got my car dynoed at dyno day, and they said my car was running a little rich.. Which is gd news since mine use to spike a fair bit.
But i have just turned my boost down a bit and doesnt spike at all past 1 bar.
SO my suggestion is just turn the boost down a little..