turbo l61 ecotec j-boby tuning question

hi all

:pray:
here my question
i am trying to tune my AFR but i am already set at 120 of ve offset and this is too lean when wot with boost
what need i to do?
does i need to change my injector constant ? explain plz
does i need to increase my ve offset to allow more than 120% and what is it the limit can i increase ? explain plz
does i need to change my injector once a time for bigger one ?

i join my tune and a log street tune ( see at 24 second )

here a quick list of my modification ( sunfire 2003 manuel ecotec l61 )
2.2 ecotec forged with cam
running 28 psi of boost ( turbo )
75 lbs lucas injector
fuel pressure increase is 1 for 1
map 2.5 bar ( i know it cannot read the entire boost but idc, iam always wot anyway )
injector constant is set to .15050

sorry for my English if its not perfect :P