Probably not going to get a lot with 91 and a stock downpipe. Probably about 17 psi peak target from 4,500-5,000. Work your way up to that in half psi increments and then taper down the same. Set boost safety to 20. FOL to 60 to start
Thanks - I apologize, it's 92, don't know where my head was. Premium in WA state is 92.