Actually if you look at CobraBobs website, youll see what pulley combos make for boost.... Or averages. Go to....
http://stangshiftergaskets.com/2003_...m#_Toc35092361
and then go to section 3.6.1 and youll see what your combo is making. A 2.93/4lb combo only makes about 15.3-15.5lbs of boost.... A 2.8/4lb is making right at 16lbs of boost.... I should know too since thats the combo I run. I dont see my car making anywhere near 19-20lbs of boost.