Are you on roller blades when you are hitting the puck on the street? If not, your skates on the ice will make you about 3 inches taller. This could be the problem.
For good steet ammunition, I use squashed beer cans. Compress them till there about 1 inch thick. It gives you a good puck sized target, and they loose there energy quickly so there is less of a chance of breaking car windows or the like.
Also, try to have your stick contact the ice about 6-8 inches in front of the puck during your swing, this will cause the stick to flex and give you the good snap your are looking for. This does however tear up the street sticks a little bit.