Slight delay when I hit the gas
 

When I rev my engine there is a delay before the engine actually revs. How should I fix this.

these are some of my mods
GT 40 Upper and lower intake manifolds
GT 40 heads. crane roller rockers
X- Cam, underdrive pulleys, Speed density comp., 110 g.p.h Fuel pump.
I only have 19# injectors.