Yep it'll be 150bhp, although 190bhp+ is only a remap away

makes it feel much more punchy.
Being a '99 and therefore an AGU engine, you -should- be able to run a blow-off valve without any fuelling issues. You can't turn them off, although its not a bad idea... all it would take is some kind of custom valve/tap to re-circ the air as is originally intended.