well its not necessarily better. but for your conditions/ YES its better.

your originally had, 4 20w. not sure the output on those, I have never seen a 20w bulb. it prob is a 23/24w

a 24w bulb is 1750 lumen
a 23w is 1600 lumen

4x1750 = 7,000 lumen. plenty to grow green.

when you flower, add 4 more, and spread them out, in a row on top pointing Sideways

start by:
add 2 more. and see how the heat is. if its good.
then add 2 more,.. get it!>?

8 bulbs should be perfect for that space, get some Fans too!