like said above ur limited to your turbo, i doubt its any good much over 14 psi so as at the moment on your spec i would say 160-180bhp depending on injection system and how its setup,

250 bhp will come with as said a stage 3 turbo, 20 psi+, grs,pro alloy etc i/c, proberly a 5th injector, may get away with it on your bottom end providing u have arp bolt set in it, but at high boost ur better off with low compression pistons