It shouldnt spike from 0.6 bar to 1.1bar,You still have a problem. Also 1.1 bar will destroy that little t2 and is completely pointless. There is no point in going more than 12psi on the standard turbo.
Have you removed your 'pov' safety valve on your inlet manifold?
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Just found a picture of your engine bay, Get rid of that diaphram dump valve and see if it still does it and im assuming those boost hoses have jubilee clips on them now
