Thanks man. The plan is to tune the car soon. But its my girlfriends car and priority is mainly on my big turbo car and i came across a great deal on the is38. I figured why not test the waters a little with it. If anything it will hold peak boost better than that tiny is12.No reason why not but I'd hardly think you were getting the most from it. Without a flash, there's only so much boost you can use without more alcohol and even with that, there's a timing/boost/ fuel constraint without a tune. I suppose you could run out of fueling with enough but if you just want to get the i38 for now and get some more ponies for a while before you take it further, should be fine. You only need enough fuel for the boost it can hold and that won't change much without outside of high RPM and/or more e30 in the mix or a tune.
Still useful to add boost and fuel pressure now and fine tune a flash when you get that.
PS. Thanks for the info.