Lets ASSUME for our example here we have a TBI setup with 2 80lb/hr injectors and a MPFI setup with 8 20lb/hr injectors (This will make numbers easy
Okay so again ASSUMING we give both systems the same net increase in pressure we can easily find out the extra flow.
(Since percentages are out of a 100 it is import to divide our figure of 3% by 100 to obtain .03)
20lb/hr*.03 = .6 <-- This means that we will gain .6 lb/hr per injector
20.6*8 = 164.8 lb/hr
80lb/hr *.03 = 2.4 <-- This mean that we will gain 2.4 lb/hr per injector
82.4*2 = 164.8 lb/hr
WOAH!!! this is of course assuming we give each setup the same increase in fuel pressure from factory which we can give the TBI system a larger increase since it was setup to run from 15-18psi.