I noticed a HUGE difference when I switched out the 318 for the 440. Compared to the small block, my car handled like it had a cow sitting on the hood. And that was with the upgraded "Hemi" suspension to handle the big block. FWIW 400hp small block and 400hp big block make the same power. You'll get more torque from the BB, but you'll have more weight to carry and it won't be as nimble on the street.