help wit swap 2.0 TO 2.5

[srpvene]

i have a subaru bug eye 2001 i have a 2.5 short block whit 2.0 heads a gt 35 hybrid turbo bolt on 850 inyertor fuel pump walbro 255 perrin fuel rails and a stock ecu tuned by my self i am triyng to see how can i make my car go faster because the turbo lag ist killing me i am running whit 38 degrees of timing from 0.50 to 1.80 of engine load but the lag ist to big and my air fuel its runing in 13.4 how can i reduce the lag