I'm on my 2and tank of e30. Similar conditions. Best I could pull was a 6.6. Something just has to be wrong with this damn car. Boost was reading at about 13.9. SOMETIMES I could get a 15.4. I know its actually boosting more with the bluespark. But I think it should be reading up to 17.1. ALSO, on a lot of runs, if I floor it boost would only read 10.9 maybe 12.1, but if I give it 3/4 throttle, especially going up hill I'll see 15.4. I did put on a GFB t9011 as well, figured that would only help. WTF...
Also my catch can on the pcv has a slight leak somewhere on near the hose going into the top of the can. Could that be causing any issues?
Maybe my testing equipment is bad. maybe I have a bad bluespark, I know when I first put it on I couldn't get any traction, thing ran like mad, now it's just not the same...