imo, your sterotypical graffiti letters are a solid color in the middle with a big border. i agree the inside should be white and a thick maroon border would work nicely. and on top of that....it might look really kewl if u did a slight transparency so as to "pull" the texture out of the wall so that it actually looks like it was sprayed on there.
and mebbe the brick texture should be larger too...the bricks are really small..if they were bigger it would give better dimensions i think.
otherwise, nice colors, and nicely done on the fire...it aint easy.