how much of a difference can i expect from installing a fuel pressure regulator on with stock injectors with the mods i have below in my sig. and if i get bigger injectors, would that help?
Not required..stock pressure is ideal for where you're at and an injector upgrade is still aways off for you as well. With a decent head upgrade you might want to look at a set of 24 pounders but still run stock fuel pressure setting. At over 300rwhp I do use the 24's but run stock fuel pressure setting of 40...and that's after a dyno tune session.
i got mine a long time ago. while naturally aspirated i never noticed much difference with it, on the dyno i picked up maybe 5 horse with small changes i think.
once i added boost and my FMU started cramming too much fuel into the engine i took FP out of it and it helped out. but i plan to get a tune to cure this.