For those that don't know, the vac ref'd pressure reg is sort of a crutch to get more fuel under load to keep from leaning out, while not running rich at idle. The *real* solution is to burn chips and adjust the pulse width (among other things) to run higher pressure across the board with no rich/lean anywhere. The vac ref is a "big hammer" approach and will still leave you with some rich/lean points in your map, just not nearly as bad and the "ends" will often be much better (particularly on a hotter than stock motor) than you could otherwise achieve without burning your own chip. Buring your own chip and setting accurate VE tables is more like using a micrometer adjustment instead a big hammer to line things up...
For example, I run my pressure WAY high for a typical TBI, but have a “perfect” BLM/INT of 128 +/-1 at near idle and high MAP areas and it pretty much keeps it close over the full range, all with no VRFPR and over 20 psi of pressure. With more tuning time (more than I’m inclined to fool with) I could get better still, AND add in more timing, WOT enrichment, and all sorts of other things. But I find my current chip good enough for now, though I may revisit if/when I ever get bored…