This explosion is meant to be in large groups, nes style. Smoke should've been in a seperate sequence.
The explosion would have to expand more. You got the colors down, they are great.
Maybe the smoke part should last a little longer, as to mark the lightness of smoke in comparison with the brevity of the explosion itself.
Its nice, thought it looks like an exploding sun :D
Try making the smoke rise after the explosion. Looks good.