Since you are not running that much boost I would think you could go to the mid to upper 20's-low 30's.
Need to get that intercooler installed though.
That should help w/you to get higher total timeing.
My Syclone likes about 20-24 degrees total depending on conditions,gas used, but that is a different animal, computer controlled, knock sensor ,etc.
Plus,, stock they (Syclones/Typhoons) boost to 14 psi,my boost I set to 18-24 psi with my chip I run.
Now w/you only running 3 psi boost pressure I could see you running upper 20's - low 30's degrees total timeing, on pump gas.
Just remember,, my Syclone has a knock sensor so when it hears knock,the ECU will pull out timeing therefore saving my engine from blowing up.
Keep us posted on your findings.
MBHD