Thats what I'm kinda doing saving all in 100X100 and resizing em then. But well im not veteran enough to do so cool explosives and effects without little help like this^^ But I'm sure I can cut it into under 2mb with removing frames.
EDIT
Now its exactly 5MB for 2 explosions sprites
Oh and my shockwave effect done with particles takes 3.5MB so they aren't too light either