As aforementioned give the leaks a good check out, could even be a split gasket on the DV thats causing the boost to be a bit freaky and lumpy. dodgy MAF (or dirty) / Boost Controller/ TGV's lots of options to why the 3K engage.

My blob used to come onto boost at 3K and found out my TGV's were dropping a little which was causing the boost unable to come on until above 3K. they are now jacked open and im changing to an STI8 manifold to erradicate the problem.

before you ask what the TGV's are their full name is tumble generator valve, if you google it there should be stacks of info abut for you

 

i have heard a few people say that the baileys dump valves aren't the best for scoobs, might be worth either putting the standard piping back on or find a known to be working DV and see if that makes a difference, as said could also be the boost controller, a cheap manual controller would bypass the standard one and not be as expensive as the original unit just in case it's not that