timing help?

[Kroner96]

Can adding fuel without timing lower boost? I took off the factory system that was fed by a FASS and ran it straight to the pump. I can tell I gained more fuel but my boost numbers went from low 50s to 41-42psi. If I add more timing could I get my boost numbers back to where they were or maybe higher? How much timing could be run with just headstuds? Ive heard 20-21. Thanks all