The stock fuel regulator attached to the fuel rail doesn't allow enough fuel to be returned to the tank, since the hi-flow pump is sending so much more fuel that is unused at idle.
You can swap it out for one from an SVX ($100 new or find one at a junk yard) and it will take the idle pressure back down to 33-35ish.
That is what I did and now I run 34 at idle and about 65 at WOT, just running 6 psi for now.
I think 100psi of fuel is a bit much. I wonder what the stock lines are rated at...