What I have found is there are many different components on the race cars, fuel system included, that can limit how fast the car can go if they are not good enough
I had one new Holley 9375HP Dominator carb. that came with a .110 needle and seat in the front and a .120 size in the rear, that motor needed more fuel on the front four cylinders and I couldn't jet the primary up enough to get the plug reading correct until I change that needle and seat to .120 like the back had in it
I hate Murphy