Build your own adjustable fuel pressure regulator ;)

[Bean]

very nice write up Dan

after a quick search I found this how-to and wondered if one would cut the 4A-GE regulator just flush between the flatish surface and vacuum nipple (without cutting too deep to not harm the spring), if this would make the need for the modification redundant - not sure if there is a 1.5-2mm gain to be had from that but maybe worth a shot. Only concern I'd have that way is if the top surface where the B&M is resting on collapses/folds...

on another note have you made any measurements (bolt spacing, diameter and depth of the piece that goes into the rail)?

if I remember correctly bolt spacing is 39mm and the protrusion is 10mm deep on a 11m diameter - I'm not sure on these figures at all though.

reason I ask if I'm not completely mistaken the Impreza WRX (GDB; 2010-) uses the above dimensions. Most Nissan, Mazda and other Subaru have the same dimensions for the protrusion but the bolt spacing is only ~32mm. Last but not least Hondas have the same bolt spacing (some are offset!) but no protrusion at all but seal with an O-ring.

PS: stock pressure at idle on the 16V (I assume 20V too) is 38-44psi (2.6-3bar) with vacuum signal disconnected and 30-33psi (2-2.3bar) with vacuum signal.