yea the fuel pump is probably the problem. also check your carbs are opening fully, often the throttle is set wrong and is only opening most of the way. maybe you're leaning out at high rpm, check your plugs to see if its running rich or lean. check your timing, could be out. Is it pinking or reall sluggish down low? best bet is to get some time on a dyno. I had an a12 with standard valve springs and it pulled 7 no worries, however i did notice the difference when I got doubble springs.